Assalam alaikoum wa Rahmatullaahi wa Barakaatuh
Practice of Night-prayer (tahajjud):
From the morals and manners of the Salaf would be their persistent practice of the Night-prayer whether in summer or winter. They would act by the advice of the Messenger (sallallahu’alaihi wa sallam):“Observe the Night-prayer because it was the habit of the righteous people before you, and it is something that draws you near to your Lord. It wipes away sins, prevents one from sinning and expel sicknesses from the body.” (collected by at-Tirmidhy through Bilaal and Abu Umaamah (13/64-65) in ad-Du’aa)
‘Abdullaah ibn Mas’ood (radhi Allahu ‘anhu) used to stand up for the Night-prayer when everyone had settled down to sleep. A humming could be heard from him like the droning of bees until dawn.
‘Abdul-’Azeez ibn abu Dawud (rahimullaah) would spread out his bed and put his hand on it saying, “How soft you are! But the bed of Paradise is softer than you!” Then he would stand to pray until Fajr.
The Messenger of Allah (sallaahu ‘alaihi wa sallam) used to pray until his feet would crack and his shins would swel. So it would be said to him, “You are doing this while you past and future sins have been forgiven?” So the Messenger of Allaah replied, “Should I not then be a grateful slave?” (collected by al-Bukhaari (3/14) in the chapter of at-Tahajjud, and Muslim (17/162) in the chapter of Sifat al-Munafiqeen, and at-Tirmidhi (2/204,205) in the chapter of as-Salah, and an-Nasai (3/219) in the chapter of Qiyaam-ul-layl)
Hasan al-Basri (rahimullaah) said, “Whoever left the Night-prayer, it was because of a sin he previously did.” He also used to repeat, “The Night-prayer is only heavy upon him whose sins have burdened him.” He also said, “A person does a sin by which he is prevented from praying the Night-prayer.” Lastly, “If you are unable to fast the day and pray the night, then know that you have been forbidden – your sins and mistakes have chained you down!”
‘Abdullaah ibn al-Mubaarak (rahimullaah) mentioned in “Az-Zuhd” on the authority of the wife of Masrooq (rahimullaah) that she said, “Masrooq never lived without his lower legs swelling up from the length of his prayers (salaat). I used to sit behind him weeping out of mercy for him.”