Answer
The women referred to in the Hadith are those pious women that Nabi (Sallallaahu Alayhi Wasallam) married and who could then convey to us the laws of Shari?ah concerning the personal life of Nabi (Sallallaahu Alayhi Wasallam) and who could be a means of increasing the Ummah. (Faydhul Qadeer vol.3 pg.490)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai