His immigration to Medina, following Muhammad''s
Nahj al-Balāgha|Volume 1|Book 1|Chapter 236
فَجَعَلْتُ أَتْبَعُ مَأْخَذَ رَسُولِ الله (صلى الله عليه وآله) فَأَطَأُ ذِكْرَهُ، حَتَّى انْتَهَيْتُ إِلَى الْعَرَجِ.
I began following the path adopted by the Prophet and treading on the lines of his remembrance till I reached al-‘Arj.