Jamieson, Fausset & Brown

And knew her not till she had brought forth her first-born son: and he called his name JESUS--The word "till" does not necessarily imply that they lived on a different footing afterwards (as will be evident from the use of the same word in Sa1 15:35; Sa2 6:23; Mat 12:20); nor does the word "first-born" decide the much-disputed question, whether Mary had any children to Joseph after the birth of Christ; for, as LIGHTFOOT says, "The law, in speaking of the first-born, regarded not whether any were born after or no, but only that none were born before." (See on Mat 13:55-56). Next: Matthew Chapter 2