Hadith 3:56
Jabir said that when the Prophet wished to relieve himself he went off where no one could see him. Abu Dawud transmitted it.
وَعَنْ جَابِرٍ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا أَرَادَ الْبَرَازَ انْطَلَقَ حَتَّى لَا يرَاهُ أحد. رَوَاهُ أَبُو دَاوُد
Original Reference: Mishkat al-Masabih 344