“…until the child is weaned.” Hannah’s sentence starts with “until,” which is more accurate than “after” or “once,” which many versions have. This is an emotional time. Hannah envisions herself giving up her beloved baby boy to the High Priest and then only seeing him again once a year. She does not speak in a complete sentence. She speaks in a plea, with her eyes, her tone of voice, perhaps with the shake of her head. She looks at her husband Elkanah, who had the authority in the house to force her to go, and silently asks, “Can I wait.” “Can I wait...until the child is weaned?” Elkanah, who loved her and no doubt saw her pain but understood her resolution to keep her commitment to give Samuel to be a Nazarite and serve God throughout his life, agreed to her request.
“appear before Yahweh.” The Hebrew is more literally, “appear before the face.” Hannah may have also had in mind Exodus 34:23, that the males appear before the face of Yahweh three times a year.
“stay there forever.” The Hebrew is the figure hyperbole, meaning for his lifetime.