Sunan an-Nasai 16179
In-book no 1443أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ يَحْيَى بْنِ أَبِي إِسْحَاقَ، عَنْ أَنَسٍ، قَالَ خَرَجْتُ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم مِنَ الْمَدِينَةِ إِلَى مَكَّةَ فَلَمْ يَزَلْ يَقْصُرُ حَتَّى رَجَعَ فَأَقَامَ بِهَا عَشْرًا .
It was narrated that Anas said: "I went out with the Messenger of Allah (ﷺ) from Al-Madinah to Mekkah, and he continued to shorten his prayers, and he stayed there for ten days."