Hadithcore
Sunan Ibn Majah, 1037
sahih· Darussalam

It was narrated that Ibn Abu Aws said:

“My grandfather, Aws, used to perform prayer, and sometimes he would make a gesture while praying, and I would give him his sandals. He said: ‘I saw the Messenger of Allah (ﷺ) performing prayer in his sandals.’”

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا غُنْدَرٌ، عَنْ شُعْبَةَ، عَنِ النُّعْمَانِ بْنِ سَالِمٍ، عَنِ ابْنِ أَبِي أَوْسٍ، قَالَ كَانَ جَدِّي أَوْسٌ يُصَلِّي فَيُشِيرُ إِلَىَّ وَهُوَ فِي الصَّلاَةِ فَأُعْطِيهِ نَعْلَيْهِ وَيَقُولُ رَأَيْتُ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ يُصَلِّي فِي نَعْلَيْهِ ‏.‏

References2 variants
In-Book Reference
Book 5, Hadith 235
English Reference
Vol. 1, Book 5, Hadith 1037