Responsa zu Malachi 2:21

They responded: We have already indicated to you the chosen authority¹Possibly referring to R. Isaac Alfasi (cf. Siman 2). However, the text of Rif Shabbat 22a is ambiguous on this point in question, "And you shall act in accordance with the instructions given to you," (Deuteronomy 17:11) "For he is an angel of God of Hosts, and rulings are sought from his mouth." (Malachi 2:7)