Chaturmas Vrat, or Chatur Mas Vrat, is observed for a period of four months and it begins from the Deva Sayana Ekadashi in Ashadh month and ends on Utthana Ekadashi in Kartik Month. The four months of Shravan, Bhadrapad, Ashwini and Kartik are considered as the holiest months in the Hindi calendar. Different types of vows and Vratas are observed by Hindus during this period.

It is believed that Hindu gods and goddesses are at rest. This period is referred to as Chaturmas – four months. Since gods and goddesses at rest can get enraged if disturbed during this period, it is customary not to organise auspicious occasions like weddings, moving into a new house, establishing a temple, organising a community prayer or other auspicious activities. These activities are renewed only after the gods and goddesses have completed their rest on the 11th day of Kartik

Katha (Story):
You may wonder how did this Vrat come about and what is the significance of Devashayani (When the God sleeps) and Devprabodhini (When the God wakes)? It is explained in the Bhagavata Purana.

The Asuras and Devas, bitter enemies though they maybe, are brothers. Their father is Maharshi Kashyapa and their mothers are his two wives Diti and Aditi respectively. Who are also btw sisters the daughters of Tvastr Prajapati. Although Prajapati is properly the name of Brahmaji, his mind-born sons such as Tvastr, Kardama, Daksha etc. are called Prajapati because the actual work of creation was done by them. Thus another name of Brahmaji is Pitamaha or Grandfather as the entire creation is the children of His children. Only the youngest, Narada refused to take part. He realized that as vast and magnificent as this Brahmanda is, it is insignificant and momentary compared to Bhagavan. Enraged, Brahmaji cursed him to wander forever through the worlds but Narada Muni took it as a blessing, the chance to meet all the various Bhaktas and watch them praise Shri Hari.

Because their mothers are Dit and Aditi respectively, the Asuras are called Daitya and the Devas are called Adityas (Especially Suryadev who is the oldest.) The difference between the two can also be explained by their mothers names. Diti is what is finite and Aditi is infinity. It is explained in the Chandogyopanishad and elsewhere that both the Devaraja Indra and the Asura raja Virochana had an opportunity to study Brahmavidya. But Virochana thought it meant “There is nothing but the self so one can do whatever one likes.” Indradeva on the other hand was able to understand the true meaning, that the self is beyond the limits of the petty whims and desires that make up the mortal body. For this reason, Bhagavan favours the Devas over the Asuras.

But the good guys don’t always stay good and the bad guys don’t always stay bad. Sitting in Amaravati his palace in Swarga, Indradeva became puffed up with pride and forgot the true source of his power. Meanwhile in Naraka, Bali the son of Virochana was thinking. Realizing the error his father had made, he resolved to purify himself of all evil and engage in rigorous tapa. Because of this the Daitya were able to overcome the Devas and Indra was dethroned. For all its exaltation and power, to be Indra is just an office. Just as through had work one can hope to be promoted in ones job, through earning much Punya one can hope to be promoted to the post of Agni, Surya, or even Indra. But the converse of that is that through the accumulation of paapa, one can lose that position again. In the Vishnu Purana there is a story of how once Bhagavan showed Indradeva a line of ants winding their way at the foot of his throne all of which had once been an Indra in a former life than sunk all the way down to the condition of an insect. Thus a wise man should realize the ultimate futility of karma and seek Vairagya alone.

Accompanied by the Devas, Indra went to Goloka and begged Vishnu Bhagavan to save him. Bhagavan who is ever merciful to his Bhaktas agreed. He took the form of Vaman a Batuk or 8 year old Brahman boy. Shiva Bhagavan takes a similar form in his Batuk Bhairava rupa. Bhagavan went to see Bali who received him cordially and offered him a gift. Bhagavan in his Vaman rupa asked him for enough land to cover three steps. Looking at the little legs of the boy in front of him, Bali burst out laughing and urged him to ask for more. But Bhagavan was adamant so Bali granted the strange request. Immediately, Bhagavan grew to collossal size. With one stride he covered the Earth and with a second, the heavens. Laughingly he asked Bali “I have covered everything and still have one step to go. Where shall I put it?” This btw is why one of His names is Vikram or Trivikrama. “Who takes (three) wide steps.” Bali realized who he was dealing with and immediately offered up his own head for the third step. This is the sign of true nobility. When he was left with nothing Bali gave up his own head rather than break his word. Bhagavan took the third step and crushed Bali back down to Naraka again.

Pleased with this display of devotion, Bhagavan went to visit Bali and offered him a wish. Bali replied “As I provided the third step, I request that you together with your wife Lakshmiji should come and live with me one third of the year. Bhagavan agreed and since then we have observed the Chaturmas Vrat. During this time, Bhagavan is considered to be asleep. Thus the start of Chaturmas is called Devashayani Ekadashi and the day Bhagavan wakes up and Chaturmas ends is called Devprabodhini Ekadashi.

Whomsoever will hear this Katha (story) of the great Bhakta Bali and practice the Chaturmas Vrat will have the blessings of Vishnu Bhagavan forever.

Rituals & Importance:
Swami Sahajanand (Swaminarayan Sampradaya) in his Shikshapatri has given 8 ways of performing this Vrat and even though he was a Visishtadvaita, his advice is suitable for Smartas too.

Vishnoh kathayah Shravanam vachanam gunakirtanam
Mahaapuja mantrajapah stotrapaathah pradakshinah 77

Saashtangahpranatishcheti niyama uttamaa mataah
Eteshvekatamo bhaktayaa dhaaraniiyo visheshatah 78

To listen attentively to the stories of Vishnu Bhagavan, or to recite them, or to sing (bhajans) in His praise. To do Maha puja to His Murti, to chant his mantras (explained by the commentator as his names as in i.e. Vishnu Sahasranama.) and stotras. To do Pradakshina and bow down to His Murti, these are regarded as the most fitting additional duties. One or more should be observed with Bhakti.

The four months is of great importance to Lord Vishnu devotees as this period is believed to be the night of Vishnu. Vishnu devotees listen to his stories and spend time in helping the poor and in cleaning and maintaining Vishnu temples.

Most people decided to read the Mahabharata or Ramayana or Gita or Srimad Bhagwat Puran during the fourth month period. Some people make it a point to visit temples daily and indulge in spiritual activities.

In the Padampuran, Srimad Bhagwat Puran and other religious texts, this rest period is referred to as Yognidra, a term that describes the rest Vishnu took after annihilation of the world. This term is also used when Vishnu is in deep meditation and cannot be disturbed. The inability to be available to devotees is termed as sleep or rest.

The Vrat ends on Kartik Shukla 11 or Devprabodhini Ekadashi. (But Swami Sahajanand (Swaminarayan Sampradaya) notes that if a Bhakta is too physically weak to maintain the Vrat for four months, he may observe it for the month of Shravan only.)

Shravan month is of great importance to Lord Shiva devotees. The Mondays in the month are highly auspicious.

Importance is given to maintaining a healthy body during the four months, as the first two months are the peak monsoon season. Due to this reason, in some regions people avoid green leafy vegetables in the Shravan month. Curd, or yoghurt, is avoided in Bhadrapad month. Milk is avoided in Ashwin month. Pulses are avoided in Kartik month. Again there are no strict codes regarding food. It all depends on the person how he/she wants to observe the Chaturmas Vrat.

Devashayani Ekadashi. For Grihasthas it is the beginning of the Chaturmas Vrat. There is also a Sannyasi Chaturmas which starts on Ashadh Poornima which I won’t describe here.

There are no hard and fast rules regarding the Chaturmas Vrat. It is often left to the devotee to decide how he/she wants to spend the four months.

Many people avoid non-vegetarian food during the four month period. Some people observe flexible fasting – eating just one meal or two, or just one meal on particular days in the month. Certain food items like jaggery or oil is avoided during the period or in any one of the four months. Some people avoid salty and sweet preparations. Those people who plan to undertake serious vows and fasting avoid garlic and onion as it can stimulate unnecessary excitements.

Chaturmas Vrat is very ancient as evidenced by the fact that Jains and Buddhists (at least in its Sannyasi form) also practice it.