Chaturmasya – Vrat’ is observed by all – Karmis, Gyanis, Yogis and Bhaktas for the attainment of their respective ends. It is a kind of penance. But there is a difference in the mode of sadhan, as the ends of Karmis, Gyanis, Yogis and Bhaktas are different. The ultimate goal of Bhaktas is the get love for Supreme Personality of Godhead Sri Krishna(Krishna-prem).
Supreme Lord Sri Chaitanya, our most Revered Paramgurudeva (His Divine Grace Srila Bhakti Siddhant Sarasvati Gosvami Thakur Prabhupad) and our Most Revered Gurudeva(His Divine Grace Srila Bhakti Dayita Madhav Gosvami Maharaj Vishnupad), observed Chaturmasya vrat only to teach us that we should also observe this Vrat.
Sri Chaitanya Mahaprabhu observed Chaturmasya Vrat at Purushottam Dham by spending the whole time with Sri Krishna-katha.
Listening and chanting of the Holy Name, Form, Attributes and Pastimes of Sri Krishna should be mainly performed. Alongwith this we should also observe exoteric rules an enjoined in the scriptures as far as practicable.
Gourd (louki), Bean (Kidney bean, a long size bean), Brinjal, Patal, Kalmishak, Purni shak are prohibited in the four months of Chaturmasya.
All leave of plants are prohibited in the month of ‘Shravan’, curd is prohibited in the month of ‘Bhadra’, and milk in the month of ‘Ashwin’, and all kinds of tasteful food is prohibited in the month of Kartik. There are other rules also. One must contact respective acharyas for more details.
Chatrumasya vrat begins on,
a) 15 July and completes on 11 November (for those who observe this vrat from Ekadashi)
and
b) 19 July and completes on 14 November (for those who observe this vrat from Purnima).