Is one who rose in the last third of the night after waking up, then slept again, considered to have performed Qiyam al-Layl, or must one wake up specifically to perform it at this time? And is one who seeks forgiveness at the beginning of the last third of the night considered among "those who seek forgiveness at dawn," or must the seeking of forgiveness be immediately before Fajr, and when does the time of Sahar begin?

The time for Qiyam al-Layl (night vigil prayer) begins immediately after the 'Isha prayer and ends with the emergence of dawn. It is not a condition for attaining reward to perform it after sleeping. The verse {Their sides forsake their beds} [32:16] includes Qiyam al-Layl generally. As for the time of Sahur (pre-dawn meal time), it is the last part of the night, just before dawn, or it begins from the last third of it. It is calculated by dividing the night, from sunset to dawn, into three equal thirds, so the last third is the time of Sahur.