and odd-numbered nights may also be reckoned by counting the nights remaining, as the Prophet, peace and blessings be upon him, said:
“When nine nights remain, when seven remain, when five remain, and when three remain.”
Accordingly, if the month has thirty days, these will be the even-numbered nights: the twenty-second night will be the ninth night remaining, and the twenty-fourth will be the seventh night remaining. This is how Abū Sa‘īd al-Khudrī explained it in the authentic hadith, and this was how the Prophet, peace and blessings be upon him, spent that month. If the month has twenty-nine days, reckoning by the nights remaining will coincide with reckoning by the nights elapsed.
Since this is so, the believer should seek it throughout all the last ten nights, as the Prophet, peace and blessings be upon him, said:
“Seek it during the last ten nights.”
It occurs more often during the last seven nights, and most frequently on the twenty-seventh night. Ubayy ibn Ka‘b used to swear that it was the twenty-seventh night. He was asked, “How did you know that?” He replied: “By the sign that the Messenger of Allah told us of. He told us that the sun rises on its morning like a basin, without rays.”
Thus, this sign, which Ubayy ibn Ka‘b reported from the Prophet, peace and blessings be upon him,