Augustine of Hippo

The right thing to do, brothers and sisters, is to believe God before he pays up anything, because just as he cannot possibly lie, so he cannot deceive. For he is God. That's how our ancestors believed him. That's how Abraham believed him. There's a faith for you that really deserves to be admired and made widely known. He had received nothing from him, and he believed his promise. We do not yet believe him, though we have already received so much. Was Abraham ever in a position to say to him, "I will believe you, because you promised me that and paid up"? No, he believed from the very first command given, without having received anything else at all. "Go out from your country," he was told, "and from your kindred, and go into a country which I will give you." And he believed straightaway, and [God] didn't give him that country but kept it for his seed.