Muwatta Malik
Book 16, Hadith 34
Arabic hadith text
وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَلِيَّ بْنَ أَبِي طَالِبٍ، كَانَ يَتَوَسَّدُ الْقُبُورَ وَيَضْطَجِعُ عَلَيْهَا . قَالَ مَالِكٌ وَإِنَّمَا نُهِيَ عَنِ الْقُعُودِ عَلَى الْقُبُورِ فِيمَا نُرَى لِلْمَذَاهِبِ .
Translation
ahya related to me from Malik that he had heard that AIi ibn AbiTalib used to rest his head on graves and lie on them.
Maliksaid, "As far as we can see ,it is only forbidden to sit on graves torelieve oneself."