On the Life of the Wise Man made perfect by Instruction or, on the Unwritten Law, that is to say, on Abraham (273)

And God, admiring this man for his faith (πίστις) in him, gives him a pledge (πίστις) in return, namely, a confirmation by an oath of the gifts which he had promised him; no longer conversing with him as God might with man, but as one friend with another. For he says, "By myself have I sworn," [*] by him that is whose word is an oath, in order that Abraham’s mind may be established still more firmly and immoveably than before.