The Messenger of Allah ﷺ came upon him while he was leading the people in prayer. He intended to step back, but the Messenger of Allah ﷺ gestured to him to stay in his place, and the Messenger of Allah ﷺ prayed following the lead of Abdul-Rahman bin Awf.
أن رسول الله ﷺ انتهى إليه وهو يصلي بالناس فأراد أن يتأخر فأومأ إليه أن مكانك، فصلى رسول الله ﷺ بصلاة عبد الرحمن بن عوف.
Tayalisi (223), Bazzar (1014), Abu Yaala (853), and Shashi in his Musnad (246) all narrated it through the route of Ibrahim bin Saad (that is, Ibrahim bin Abdul-Rahman bin Awf), from his father (Saad), from his grandfather (Ibrahim), from Abdul-Rahman bin Awf, who related it. Its chain of transmission is sahih. This is a unique incident that did not happen to anyone other than Abdul-Rahman bin Awf.