Hadith 4:177
Ibn 'Abbas said God’s messenger was lowered gently into the grave head first. Shafi'i transmitted it.
وَعَنِ ابْنِ عَبَّاسٍ قَالَ: سُلَّ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مِنْ قِبَلِ رَأْسِهِ. رَوَاهُ الشَّافِعِي
Original Reference: Mishkat al-Masabih 1705