Kommentar zu Bereschit 50:16

ויצוו אל יוסף AND THEY COMMANDED SOME TO GO TO JOSEPH — The words ויצוו אל have the same meaning as in (Exodus 6:13) “and He gave them a charge unto (ויצום אל) the children of Israel”, which signifies, “He commanded Moses and Aaron to act as messengers to the children of Israel”, and this verse, too, means they charged the man whom they sent that he should act as their messenger to Joseph to speak to him as follows (the words לומר לו כן correspond to לאמר in the Bible text here). And who was it that they so charged? The sons of Bilhah who had been accustomed to associate with him, as it is said (Genesis 37:12) “When a lad he used to be with the sons of Bilhah” (Tanchuma Yashan 2:1:2).

ויצוו אל יוסף לאמור, “they entrusted the following message to discreet messengers before they themselves came to Joseph.”

ויצוו אל יוסף, they commanded Yaakov’s servants or outsiders concerning Joseph. We find a similar construction in Exodus 6,13 ויצום אל בני ישראל, where G’d commanded Moses and Aaron to address the Israelites.