Abu al-Qa'qa' (may Allah have mercy on him) said: I was present at al-Qadisiyyah when I was a boy or an adolescent. A man came to Sayyiduna Abdullah (may Allah be pleased with him) and said: May I come to my wife however I wish? He said: Yes. He said: As I wish? He said: Yes. He said: From wherever I wish? He said: Yes. A man understood (his intent) and said: He wants to have intercourse with her in her backside. He said: No; the backsides of women are forbidden to you.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14129