I think he (Abu Taiba) was her faster brother or a young boy before entering upon the adolescent period.
Sahih Muslim Book 39, Hadith 98
← Previous Hadith There came to our house 'Abdullah and another person from amongst the members of the household who complained of a wound. Jabir said: What ails you? He said: There is a wound which is very painful for me, whereupon he said: Boy, bring to me a cupper. He said: 'Abdullah, what do you intend to do with the cupper? I said: I would get this wound cupped. He said: By Allah. oven the touch of fly or cloth causes me pain (and cupping) would thus cause me (unbearable) pain. And when he saw him feeling pain (at the idea of cupping), he said: I heard Allah's Messenger (ﷺ) as saying: If there is any effective remedy amongst your remedies, these are (three): Cupping, drinking of honey and cauterisation with the help of fire. Allah's Messenger (ﷺ) had said: As for myself I do not like cauterisation. The cupper was called and he cupped him and he was all right.

Sahih Muslim Book 39, Hadith 97 Next Hadith → Jabir reported that Allah's Messenger (ﷺ) sent a phystian to Ubayy b. Ka'b. He cut the vein and then cauterised it.

Sahih Muslim Book 39, Hadith 99