[Machine] I entered upon the Messenger of Allah ﷺ while he was observing I'tikaf on a Tuesday, so I said, "Do you observe I'tikaf on this day?" He said, "Yes, whoever of you coincide with the night of the seventeenth from the month of Ramadan, should continue observing I'tikaf until he completes it, so you all should also observe I'tikaf."
دَخَلْتُ عَلَى رَسُولِ اللهِ ﷺ وَهُوَ يَحْتَجِمُ يَوْمَ الثُّلَاثَاءِ فَقُلْتُ هَذَا الْيَوْمَ تَحْتَجِمُ؟ قَالَ «نَعَمْ وَمَنْ وَافَقَ مِنْكُمْ يَوْمَ الثُّلَاثَاءِ لَيْلَةَ سَبْعَ عَشْرَةَ مَضَتْ منَ الشَّهْرِ فَلَا يُجَاوِزُ حَتَّى يَحْتَجِمُ فَاحْتَجِمُوا»