I saw Ibn Umar make his camel kneel facing the qiblah, then he sat down to urinate toward it. I said, "Abu Abdul-Rahman, has this not been forbidden?"He replied, "Yes, but that was forbidden only in open ground. When there is something between you and the qiblah to screen you, there is no harm in it."
حدثنا محمد بن يحيى بن فارس حدثنا صفوان بن عيسى عن الحسن بن ذكوان
رأيت ابن عمر أناخ راحلته مستقبل القبلة ثم جلس يبول إليها فقلت يا أبا عبد الرحمن أليس قد نهي عن هذا قال بلى إنما نهي عن ذلك في الفضاء فإذا كان بينك وبين القبلة شيء يسترك فلا بأس
[Its chain is daif] Bayhaqi narrated it (1/92) from the hadith of Abu Dawud through him, and Ibn Khuzayma graded it sahih, no. 60, as did Daraqutni (1/58), and Hakim did so as well according to the criterion of Bukhari (1/154), and Dhahabi agreed with him, and Hazimi graded it hasan in Itibar fi Nasikh wal-Mansukh min Akhbar.Hasan bin Zakwan conceals defects in his transmission, and I did not find an explicit statement that he heard it directly.