knew her. Heb, idiom, and Figure of speech Metonymy (of Adjunct) for cohabitation. Note the imperfect tense. was not knowing. See App-132.
till. Mat 12:46-60. Matthew 13:55; Matthew 13:56, clearly show that she had sons afterwards. See the force of this word heos in Matthew 28:20, "unto".
her firstborn Son. These words are quoted by Tatian (A.D. 172) and twelve of the Fathers before cent. 4; and are contained in nearly all MSS. except the Vatican and Sinaitic (cent. 4). All the Texts omit "her firstborn" on this weak and suspicious evidence. But there is no question about it in Luke 2:7.
he: i.e. Joseph