Fayz Kashani, and his book “Wafi”:
Narration #1:” (From Tahtheeb) From Ahmad, from Bargi, from imam Abu AbdAllah (a.s): “If a man has an intercouse with his wife into a**s, and didn’t ejaculated then none of them should make “gusl”, if he did, then he should do “gusl”, but she shouldn’t”.
Narration #2: “(From Tahtheeb) From ibn Mahjoob, from some Kufians, which asked imam Abu AbdAllah about a man, which has an intercouse with his wife into a**s, while she was fasting. He said: “She shouldn’t stop her fast, and there is no need to her to perfom ablution”.
And third narration with the same meaning like second one.