Mishkat al-Masabih 4 Prayer كتاب الصلاة 375

وَعَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ قَالَ: كَانَ أَكْثَرُ انْصِرَافِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مِنْ صَلَاتِهِ إِلَى شِقِّهِ الْأَيْسَرِ إِلَى حُجْرَتِهِ. رَوَاهُ فِي شرح السّنة

‘Abdallah b. Mas’ud said that the Prophet most commonly turned to his left after his prayer, going to his room. [Baghawi] transmitted it in Sharh as-sunna .