Musannaf Ibn Abi Shayba 1:992

Abu Usama narrated to us, from Hisham, from al-Hasan, regarding a man who engages in sexual activity with a woman other than through her private part: He said: "If she ejaculates, she must perform ghusl (full ritual bath). If she does not ejaculate, she must perform wudu (ablution) and wash from her body whatever the man’s fluid has touched."