Greek Expositor
Catena Aurea · Lukasevangelium 2
And it came to pass in those days, that there went out a decree from Cæsar Augustus, that all the world should be taxed. (And this taxing was first made when Cyrenius was governor of Syria.) And all went to be taxed, every one into his own city. And Joseph also went up from Galilee, out of the city of Nazareth, into Judæa, unto the city of David, which is called Bethlehem; (because he was of the house and lineage of David:) To be taxed with Mary his espoused wife, being great with child.
(Irenæus cont. Hær. 1. 3. c. 11.) Now he added, a city of David, that he might declare that the promise made by God to David, namely, that from the fruit of his loins there should go before him a king for ever, (2 Sam. 7:12.) was already fulfilled. Whence it follows, Because he was of the house and lineage of David. (Ps. 132:11.) But since Joseph was of the family of David, it pleased the Evangelist to make known also that the Virgin herself was of the same family, because the Divine law enjoined marriages between those of the same line; and therefore it follows, With Mary his espoused wife.