Sahih Adab al-Mufrad

Bukair narrates that he saw Sayyiduna Abdullah bin Ja'far (may Allah be pleased with him) kiss Zainab, the daughter of Umar bin Abu Salamah. At that time, Zainab was two years old or around that age.

It is narrated from Hasan (al-Basri) that he said: If possible, do not even look at the hair of any woman in your household, except if she is your wife or a small girl, then you may do so.