BT Ned 31a(18) :כיון דאתקדש אברה׳ אתקרו על שמי׳‏ : since Abraham was sanctified they were called by his name
See the entire entry for ˁal prep. upon; against; to

BT Ned 31a(18) :אתקרו על שמי׳‏ :
See the entire entry for qry vb. to call