(This verse means) the prayer and vigil at night.

“Our Lord, the Blessed and Exalted, descends when one third of the night remains, every night and He says: ‘Who will ask of Me, that I may give him? Who will call upon Me, that I may answer him? Who will ask My forgiveness, that I may forgive him?’ until dawn comes.” Hence they used to prefer voluntary prayers at the end of the night rather than at the beginning.

“When praying at night (Qiyamul-Lail), the Messenger of Allah (ﷺ) used to say between the two prostrations: ‘Rabbighfir li warhamni wajburni warzuqni warfa’ni (O Lord, forgive me, have mercy on me, improve my situation, grant me provision and raise me in status).’”

"The Prophet (S) stood (in prayer) with an Ayah from the Qur'an at night"

In Surat al-Muzzammil (73), the verse: "Keep vigil at night but a little, a half thereof" (2-3) has been abrogated by the following verse: "He knoweth that ye count it not, and turneth unto you in mercy. Recite then of the Qur'an that which is easy for you" (v.20). The phrase "the vigil of the night" (nashi'at al-layl) means the early hours of the night. They (the companions) would pray (the tahajjud prayer) in the early hours of the night. He (Ibn Abbas) says: It is advisable to offer the prayer at night (tahajjud), prescribed by Allah for you (in the early hours of the night). This is because when a person sleeps, he does not know when he will awake. The words "speech more certain" (aqwamu qilan) means that this time is more suitable for the understanding of the Qur'an. He says: The verse: "Lo, thou hast by day a chain of business" (v.7) means engagement for long periods (in the day's work).