“Verily in the creation of the Heavens and the Earth and the changing of the night and day are signs for those of intelligence…” (Al-Qur’ān, 3/190)
Imam Ibn Rajab Rahimahullāh explains that this comparison is because of the ease that Allāh Ta’ālā has created in the winter period for certain a’māl; just as an animal grazes and stores fat for the future in the green months, a Mu’min is able to “graze in the lush pastures of ‘ibādah and obedience of Allāh Ta’ālā”, thereby strengthening his soul and spirituality. Subhānallāh!
Allāh Ta’ālā has created the world and its systems such that it is not constant- there’s ease and difficulty, long days and short days, heat and the cold. One of the wisdoms mentioned for this is that a Mu’min will be tested and will have to stay firm on the commands of Allāh Ta’ālā in all conditions. Sometimes it will be easier, and sometimes he will have to fight his nafs and beat the difficulty.
However, the purpose here is to enumerate certain a’māl and rewards that have been handed to us on a plate in winter. Nabi Sallalāhu ‘Alayhi wa Sallam said: “The expiation of sins lies in performing a proper Wudhū’ despite difficulties (cold weather, cold water, etc), walking to the Masjid, and waiting for Salāh after the previous Salāh.” (Muslim, 251)
Hasan Al-Basri Rahimahullāh would say: “What a great time winter is for a Mu’min! Its nights are long for him to stand in Salāh, and its days are short for him to fast in.” The Tahajjud Salāh is a great Sunnah of Nabi Sallalāhu ‘Alayhi wa Sallam and a sure way to gain closeness to Allāh Ta’ālā. Nabi Sallalāhu ‘Alayhi wa Sallam said that “The best Salāh after the farāidh is the Salāh of the night (i.e., Tahajjud).” (Muslim, 1163)
Winter nights are extremely conducive for this Salāh; one can get sufficient sleep and still awaken early, refreshed, for communion with his Rabb.