Or HaChaim on Genesis 21:14/אור החיים על בראשית כ״א:י״ד

1 על שכמה ואת הילד. On her shoulder together with the child. Abraham put Ishmael also on Hagar's shoulder because the latter refused to leave his father's house. As a result Abraham tied him up as one ties up a child, put him on Hagar's shoulder and expelled her.