Muwatta Malik 813
موطأ مالك#813Sahihحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا قَضَى طَوَافَهُ بِالْبَيْتِ وَرَكَعَ الرَّكْعَتَيْنِ وَأَرَادَ أَنْ يَخْرُجَ إِلَى الصَّفَا وَالْمَرْوَةِ اسْتَلَمَ الرُّكْنَ الأَسْوَدَ قَبْلَ أَنْ يَخْرُجَ .
Yahya related to me from Malik that he had heard that when the Messenger of Allah, may Allah bless him and grant him peace, had finished his tawaf of the House, prayed two rakas, and wanted to go to Safa and Marwa, he would salute the corner of the Black Stone before he left
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 20:109