Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: Once I climbed onto the roof of the house of Sayyidah Hafsah (may Allah be pleased with her), and the Prophet Muhammad (peace and blessings be upon him) was present there. He was relieving himself in the toilet facing the Qiblah and with his back towards Shaam.
Hadith Referenceصحیح ابن حبان / كتاب الطهارة / 1418
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: خ.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح.