Ibn Ezra on Genesis 14:20/אבן עזרא על בראשית י״ד:כ׳

1HATH DELIVERED. Miggen (hath delivered) means handed over. Temaggeneka (will she bestow on thee) in A crown of glory will she bestow on thee (temaggeneka) (Prov. 4:9) is similar. The mem of miggen is a root letter. Abraham gave a tithe out of respect for God. He found no one worthier than Melchizedek to bestow his tithe on.