مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 3922
Jihad
Conduct while Traveling - Section 3
عَن أبي قتادةَ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا كَانَ فِي سَفَرٍ فَعَرَّسَ بِلَيْلٍ اضْطَجَعَ عَلَى يَمِينِهِ وَإِذَا عَرَّسَ قُبَيْلَ الصُّبْحِ نَصَبَ ذِرَاعَهُ وَوَضَعَ رَأْسَهُ عَلَى كَفِّهِ. رَوَاهُ مُسلم
Abu Qatada told that when God's Messenger encamped at night on a journey he lay down on his right side, and when he encamped a little before morning he raised his forearm and placed his head on the palm of his hand. Muslim transmitted it.
Mishkat al-Masabih, 3922صَحِيح (الألباني)