Bede the Venerable
Catena Aurea · Lukasevangelium 2
And so it was, that, while they were there, the days were accomplished that, she should be delivered. And she brought forth her firstborn son, and wrapped him in swaddling clothes, and laid him in a manger; because there was no room for them in the inn.
He is also only-begotten in the substance of His divinity, firstborn in the taking upon Himself humanity, firstborn in grace, only-begotten in nature.