Praise be to Allah, and peace and blessings be upon the Messenger of Allah.
It is authentically established in the two Sahihs from Abu Hurayrah رضي الله عنه that the Prophet صلى الله عليه وسلم said:
“Our Lord, Blessed and Exalted, descends every night to the lowest heaven when the last third of the night remains, saying: Who is calling upon Me so that I may answer him? Who is asking Me so that I may give him? Who is seeking My forgiveness so that I may forgive him?”
Narrated by al-Bukhari (1145) and Muslim (758).
Several narrations specify the time of the Divine descent as the last third of the night. Imam al-Tirmidhi رحمه الله mentioned that this narration is the soundest of the narrations on the subject.
If the night is divided into six sixths, then the last third consists of:
The fifth sixth.
The sixth sixth.
Therefore, the fifth sixth is the beginning of the last third of the night.
Thus, when it is said that the time of the Divine descent is the last third, this includes both the fifth and sixth sixths.
And when it is said that the time of the descent is the fifth sixth, the intended meaning is that it begins at the fifth sixth, not that it ends when the fifth sixth ends.
Therefore, there is no contradiction between the two expressions.
A narration in Muslim (758) indicates that this continues until dawn. It states:
“And He continues in this manner until dawn becomes bright.”
Accordingly, the meaning is that the descent begins when the last third of the night begins, meaning at the beginning of the fifth sixth, and continues until dawn.
For example, if the night in a particular place is nine hours long, then the last third is three hours, not merely one and a half hours.
In the example mentioned: if sunset is at 8:00 p.m. and dawn is at 5:00 a.m., the night is nine hours long. The last third begins after six hours have passed, at 2:00 a.m., and continues until 5:00 a.m.
This is the entire last third, consisting of the fifth and sixth sixths.
Some hadiths use the expression:
“The middle/depth of the latter part of the night.”
Some scholars interpreted this expression as referring to the last third of the night, which, when the night is divided into six parts, begins with the fifth sixth.
Al-Khattabi رحمه الله said in explaining this expression:
“It is the fifth part of the six divisions of the night.”
Ibn al-Athir رحمه الله said:
“The middle/depth of the latter part of the night means its final third, which is the fifth part of the six divisions of the night.”
This does not mean that only the fifth sixth is intended without the sixth, because the fifth sixth is the beginning of the last third. When it is mentioned as the first part of the last third, that does not mean that the time ends when the fifth sixth ends.
Scholars have mentioned the possibility that the fifth sixth has a particular virtue because it is the beginning of the latter part of the night and is among the times in which supplication is most likely to be answered.
It was narrated from Abu Umamah رضي الله عنه that the Prophet صلى الله عليه وسلم was asked:
“Which supplication is most likely to be heard?”
He replied:
“The middle/depth of the latter part of the night and after the obligatory prayers.”
Narrated by al-Tirmidhi (3499), and authenticated by al-Albani.
However, this does not change the fundamental point: the last third begins with the fifth sixth and continues until dawn.
There is no contradiction between the two statements:
The last third of the night = the fifth and sixth sixths.
The fifth sixth = the beginning of the last third.
The middle/depth of the latter part of the night may refer to the last third, which begins with the fifth sixth.
Therefore, according to the hadith narrated in the two Sahihs, the time of the Divine descent is the last third of the night; it begins with the fifth sixth and continues until dawn.
If the night is nine hours long, as in the example above, the last third begins after six hours from the beginning of the night and lasts for three full hours until dawn.
And Allah knows best.