Bede : But he said: Lord God, how am I to know that I shall possess it? Abraham is not to be thought to have failed in faith after he believed in God, and it was counted to him as righteousness, so as to say: Lord God, how am I to know that I shall possess it? For he is not seeking a sign to believe as if he were still unbelieving; rather, he entreats that some similarity be given to the thing he believed would happen, by which the manner of it being achieved might be recognized. Hence the old translation has more significantly: Sovereign Lord, according to what shall I know that I will be its heir? Just as there was no lack of faith in the Virgin Mary when she said: How will this be, since I do not know a man (Luke 1:34)? She was certain of what was to come, she inquired about the manner of how it would happen. And when she had asked this, she received an answer. Consequently, here too a similitude was given from the animals: a heifer, a goat, a ram, and two birds, a turtledove and a pigeon, so that he might know through these that what was to come would surely come. For it follows: — Commentary on Genesis (Hexaemeron)