Reference: http://mufti.af.org.sa/ar/content/ينزل-ربنا-تبارك-وتعالى-كل-ليلة-إلى-السماء-الدنيا
Question: Is standing [during] the last third [of the night in prayer] best? [Please advise] with clarity of the time when the last third of the night is.
Response: The Prophet ﷺ said:
And the last third of the night differs with the changing of the seasons – Winter, Spring, Summer and Autumn – so it is not possible to pinpoint a specific time [when that would always be]. The rule[1] in this [case] would be to add up the hours from sunset [at Maghrib] until the arrival of Fajr [the following day], then divide that equally into three, and with that the last third of every night will be made apparent to you.
Translator’s note:
[1] For example, if the time for Maghrib is 7pm, and Fajr is 4am the following day, the number of hours between the two would be 9 hours. So dividing 9 into 3 would give us 3. With that, the last third of the night will be determined as having started 3 hours before Fajr, at 1am.
