ENOfficial
Abu Qatada said: “When the Prophet (Allah bless him and give him peace) alighted for rest at night, he would recline on his right side, and when he alighted for rest shortly before the morning, he would raise his forearm and place his head on the palm of his hand.”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا الْحُسَيْنُ بْنُ مُحَمَّدٍ الْجُرَيْرِيُّ، قَالَ: حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، قَالَ: حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ حُمَيْدٍ، عَنْ بَكْرِ بْنِ عَبْدِ اللهِ الْمُزَنِيِّ، عَنْ عَبْدِ اللهِ بْنِ رَبَاحٍ، عَنْ أَبِي قَتَادَةَ: أَنَّ النَّبِيَّ صلى الله عليه وسلم، كَانَ إِذَا عَرَّسَ بِلَيْلٍ اضْطَجَعَ عَلَى شِقِّهِ الأَيْمَنِ، وَإِذَا عَرَّسَ قُبَيْلَ الصُّبْحِ نَصَبَ ذِرَاعَهُ، وَوَضَعَ رَأْسَهُ عَلَى كَفِّهِ.
sunnah.com