Musannaf Ibn Abi Shayba 9:749

Ibn ‘Ulayyah narrated to us, from someone who asked Yunus about a man who buys a slave woman and seeks to establish her purity (istibra’): may he engage in kissing and physical contact with her? Ibn Sirin said: "It is disliked for him to engage in anything with her that is forbidden for him with others until he establishes her purity." It is mentioned from al-Hasan that he saw no harm in kissing.