Do not be afraid translates the same construction used in Matthew 28.5.

Go and tell my brethren to go to Galilee, and there they will see me is now rendered as a command of the risen Lord himself; it was given as a statement by the angel in verse 7.

Brethren are not the biological brothers of Jesus, but rather his disciples (see verse 16). One way to translate is “my disciples, who are like brothers to me,” but this is a little cumbersome. “My closest friends” has also been used, and “the ones I love like brothers” is another possibility.

Quoted with permission from Newman, Barclay M. and Stine, Philip C. A Handbook on the Gospel of Matthew. (UBS Handbook Series). New York: UBS, 1988. For this and other handbooks for translators see here .