Hadith.2924 - Ibn Faddal narrated from Yunus ibn Ya'qub, who said
I sent a message to Abu Abdullah (as) asking about the mother of a woman who was a concubine (umm walad). She had passed away, and the woman wanted to perform Hajj on her behalf.
Imam (as) said: "Did she not gain her freedom through her child? She may perform Hajj on her behalf."