It is narrated from Hazrat Khuzaymah bin Thabit (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) forbade a man from approaching a woman from her "rear part."
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 21850
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد ضعيف لإبهام راويه عن خزيمة