On the Authority of ʿĀʾishah, may Allāh be pleased with her, who said: “When the last ten nights would enter, Allāh’s Messenger (ﷺ) would stay up throughout the night, awaken his family, become intense (in worship) and tighten his miʾzār (lower garment).” (Agreed upon)

What is intended here is: The last ten nights of Ramaḍān. miʾzār is: the Izaar. Meaning: to withdraw from women. And it is said that the intended meaning is: Girding himself up for worship. It is said: “I tightened my miʾzār for this matter.” Meaning: I girded myself and secluded myself for it.

Explanation:

The author (al-Nawawī) may Allāh have mercy upon him, said in what he has transmitted from ʿĀʾishah the daughter of Abū Bakr al-Siddīq, may Allāh be pleased with them both, concerning the state of Allāh’s Messenger (ﷺ) during the last ten nights of Ramaḍān, that when he entered the last ten nights he would tighten his miʾzār, stay awake throughout the night, intensify his worship, and gird himself upon it, prayer and peace be upon him.

It has already preceded concerning the preceding Ḥadīth that he (ﷺ) used to stand in the night until his ankles would become swollen and that he would stand more than half the night or half the night or one-third of the night. As for in the last ten nights of Ramaḍān, he would stand the whole night, meaning he would stay awake for the entire night, prayers and peace be upon him, in worship. However, with the breaking of the fast after the setting of the sun, dinner and the ‘ʿIshāʾa prayer, and the things which he, (ﷺ) saw as a means of nearness to Allāh the Mighty and Majestic. The meaning of it is not that he would spend the entire night praying. The evidence is that Safiyah bint Huyay ibn Akhtab used to come to him, (ﷺ) and he would speak to her. However everything which he (ﷺ) would do during those nights – it was a means of nearness to Allāh the Mighty and Majestic; either the prayer, preparing for the prayer, or other than it.

In this is an evidence that the Messenger (ﷺ) would stay awake for all of the last ten nights of Ramaḍān, but he would not stay awake for other nights beside them. Meaning, he would not stand until the morning except in the last ten nights of Ramaḍān; and that was in search of Laylat al-Qadr, and it is a night that is in the last ten nights of Ramaḍān; particularly, in the last seven from it. This is the night in which Allāh, the Glorified and Exalted, decrees what will be within that year. It is as Allāh said:

لَيْلَةُ الْقَدْرِ خَيْرٌ مِّنْ أَلْفِ شَهْرٍ ‎﴿٣﴾‏

“…better than one thousand months.”
[al-Qadr, 97:3]

So he would stay awake for it.

Whoever stands on Laylat al-Qadr out of īmān and seeking the reward from Allāh, then forgiven for him is that which has preceded of his sins.

Then the author, may Allāh have mercy upon him, mentioned the meaning of the statement: “…tighten his miʾzār.”

From them (the scholars) is he who says: It means to abandon women; because he was in a state of Iʿtikāf. Women are not permissible for the one doing al-iʿtikāf; as the Exalted has said:

وَلَا تُبَاشِرُوهُنَّ وَأَنتُمْ عَاكِفُونَ فِي الْمَسَاجِدِ ۗ ‎﴿١٨٧﴾‏

“And do not have sexual relations with them while you are in a state of Iʿtikāf in the mosques.”
[Sūrah al-Baqarah, 2:187]

And from them (the scholars) is he who says: Rather, it means seriousness and girding one’s self upon righteous action. Both matters are correct. For the Messenger (ﷺ) would not come to his family in the last ten nights of Ramaḍān because he was in a state of Iʿtikāf. He would also tighten his miʾzār, strive hard and gird himself (ﷺ) upon good. This is from the types of struggling against the soul. So it is obligatory that the person struggle against his soul in the virtuous times so that he uses them in obedience of Allāh.

Source: Taken from the Shaykh’s Explanation of Rīyaḍus-al-Ṣāliḥīn
Translated by: Raha Batts