حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَسْتَتِرُ بِرَاحِلَتِهِ إِذَا صَلَّى ‏.‏

Yahya related to me from Malik that he had heard that Abdullah ibn Umar would use the animal he was riding as a sutra when he prayed. Translation Not Available

Book Ref: Muwatta Imam Malik Book 9 Hadith 374
Web Ref:  Muwatta Imam Malik Book 9 Hadith 44