John Gill Commentary Genesis 50:18

"And his brethren also went and fell down before his face; and they said, Behold, we are thy servants." — Genesis 50:18 (ASV)

And his brethren also went
The messengers being returned to them, and acquainting them with what Joseph had said, they took courage and went from Goshen to Joseph's house or palace, be it where it may.

and fell down before his face
in an humble suppliant manner.

and they said, behold, we are your servants
they were content to be so, would he but forgive their sin, and not resent their ill behaviour to him; thus they further fulfilled his dream of the eleven stars making obeisance to him, (Genesis 37:9) .