Third month: No milk (if required, it can be mixed with a drop of lemon juice).
Caturmasya stands for ‘four months’. It is the period between sayana and uttana ekadasis. The scriptures refer to this period as the duration of Lord Visnu’s sleep in this universe.
The main goal of observing Caturmasya is to decrease attachment to material things and to increase devotion to Krishna.
Srila Prabhupada writes in Caitanya Caritamrta, “Caturmasya should be observed by all sections of the population. It does not matter whether one is a grihasta or a sanyasi. The observation is obligatory to all ashramas.” He further explains how to observe the vow: “This is not very difficult. In the month of Sravana one should not eat spinach (green leafy vegetables of the nature), in the month of Bhadra one should not eat yogurt (yogurt used as binding agent for cake is allowed), and in the month of Asvina one should not drink milk (milk sweets, milk by-products are fine).
One should not eat fish or other non-vegetarian food during the month of Kartik. Masura dal and urad dal being high in protein is also considered non-vegetarian.” Thus during caturmasya one should practice to give up all food intended for sense enjoyment. However, maha-prasad, though containing restricted item can be honoured!
It is stated in Hari Bhakti Vilasa 15/113 that ‘after properly praying to the Supreme Lord near Him, one should properly take a vow to follow the proper rules and regulations and process of caturmasya to increase one’s devotion to Lord Sri Krishna.’
So please take this opportunity and engage yourself yourselves in the service of the Lord with much enthusiasm and make your life sublime.