John Gill Commentary Matthew 27:65

"Pilate said unto them, Ye have a guard: go, make it [as] sure as ye can." — Matthew 27:65 (ASV)

Pilate said to them, you have a watch
Meaning either the watch of the temple, said to be placed in the tower of Antonia, for the service of it: hence mention is made of the captain of the temple, (Acts 4:1) , but it is not likely they would remove the temple guards, to watch a sepulchre night and day: or rather, therefore, the soldiers that had the care of the crucifixion of Christ, and watched him on the cross, are designed: the words may be read imperatively, "have a watch", or "take a watch", as the Ethiopic version renders it, and which seems best; for if they had a watch already, what occasion had they to have applied to Pilate for one? but having none, he gives them leave to take one, or such a number of soldiers as were sufficient:

go your way ;
as fast as you can, take the watch as soon as you please, make no stay, but satisfy yourselves in this point:

make [it] as sure as you can ;
or, as you know how to do it, and what will be proper and necessary.