(101) باب إِرْدَافِ الرَّجُلِ خَلْفَ الرَّجُلِ
Narrated Mu`adh bin Jabal:
While I was riding behind the Prophet (ﷺ) and between me and him and between me and him there was only the back of the saddle, he said, "0 Mu`adh!" I replied, "Labbaik, 0 Allah's Messenger (ﷺ), and Sa`daik!" he said, "Do you know what is Allah's right upon his slave?" I said, "Allah and His Apostle know best" He said "Allah's right upon his slaves is that they should worship Him alone and not worship anything else besides Him." Then he proceeded for a while and then said, "O Mu`adh bin Jabal!" I replied, "Labbaik, O Allah's Messenger (ﷺ):, Sa`daik!' He said, "Do you know what is the right of the slaves upon Allah if they do that?" I replied, "Allah and His Apostle know best." He said, "The right of the slaves upon Allah is that He will not punish them (if they do that).
Reference: Sahih al-Bukhari 5967
In-book reference: Book 77, Hadith 183
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 7, Book 72, Hadith 850