Before I forget, as I did yesterday, 9 October was the feast of St. Abraham, partriarch of the Old Testment. Here is the entry in the newest edition of the Martyrologium Romanum with a translation:
3. Commemoratio sancti Abrahae, patriarchae et omnium credentium patris, qui, Domino vocante, ab urbe Ur Chaldaeorum, patria sua, egressus est et per terram erravit eidem et semini eius a Deo promissam. Item totam fidem suam in Deo manifestavit, cvm, sperans contra spem, unigenitum Isaac ei iam seni a Domino datum ex uxore sterili in sacrificum offerre non renuit. … The commemoration of Saint Abraham, patriarch and father of all believers, who, since the Lord was calling him, went froth from the city of Ur of the Chaldeans, his home land, and wandered through the land promised by God to him and to his seed. He manfiested his complete faith in God when, hoping against hope, he did not refrain from offering in sacrifice his only-begotten son Isaac, given by the Lord to him, an old man, from his sterile wife.
Nothing is impossible with God.
For the Fathers, Abraham is a great "type" or foreshadowing figure. Some, such as St. Ambrose (+397) for example, and St. Jerome (+420) took his journey from Ur to the Promissed Land to exemplify the journey of purification necessary for union with God. For Origen, his obedience in offering up Isaac as faith in the resurrection. Others see Abraham and Isaac, ascending the hill for the sacrifice, as, together, a foreshadowing of Christ the Priest who is also Victim.
A propos the limbo debate these days, the "bosom of Abraham" is considered sometimes as an intermediate place between heaven and hell where the just are consoled while awaiting the final resurrection (this is what Tertullian thought) or the refuge of eternal peace (Ambrose, De obitu Valent. 72).