It is narrated from Sayyiduna Abu Umamah (may Allah be pleased with him): One day the Messenger of Allah (peace and blessings be upon him) was sitting and a woman was with him (peace and blessings be upon him), when the Messenger of Allah (peace and blessings be upon him) said to her: "I think that you women tell what your husbands do with you (in marital relations)." She said: Yes, by Allah, may my father and mother be ransomed for you, O Messenger of Allah, we even take pride in it. The Messenger of Allah (peace and blessings be upon him) said: "Never do that, for Allah is intensely angry with the one who does it."
He (peace and blessings be upon him) said to her: "I think that when the husband of one of you comes to her, the two of them throw off the quilt and each looks at the other's private parts as though they were two donkeys." She said: Yes, by Allah, may my father and mother be ransomed for you, we do that. He (peace and blessings be upon him) said: "Do not do that, for Allah is intensely angry at it."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7813