This contradiction, which builds upon #38, was also formed as the result of an editorial process that stitched together the Yahwist and the Priestly sources. Simply put, the Yahwist tradition accredits Yahweh’s angel with the naming of Ishmael, playing of the etymology: “And you shall call his name Ishmael, for Yahweh has heard (shama‘) your suffering” (Gen 16:11).
Yet consistent with his reinterpretive agenda, the Priestly writer does 2 things in rewriting this passage: 1) he eliminates any mention of angels from his narrative (we will see the Deuteronomist do the same thing when he renarrates earlier stories with angels in them); and 2) he places Abraham as the central focus of the narrative. “And Abram called the name of his son Ishmael.”
This and the previous contradictions that we have been looking at amount to minute changes in the narrative details of how the story was told in different geographies, in different historical circumstances, and to different audiences. In some cases, such as in the case of the Priestly writer, these changes were done to suit the concerns of the new historical audience that this story was now being addressed to, and to interject into the story the theological views of the scribe or the elite community he represented.
Did mothers ever get to decide their children’s names in Bible times, though? All that an untrained reader will see here is an angel telling Hagar what the baby’s name should be, and then the father actually giving it that name. According to this way of reading the text, Abraham simply thought it a good idea to believe Hagar when she said an angel gave her the name, and made it official. The only part of such a reading which is not explicitly stated is a bridge like “…and Hagar told Abraham what the angel said.”, which the reader could be expected to fill in using common sense.
Mothers typically named their children. To shoehorn in a bridge here is just “making stuff up”.