This was a violation of the Law which was given to Moses for the nation of Israel. This can be made explicit. AT: "by eating meat without draining the blood first as required by the law" (See: [[rc://en/ta/man/translate/figs-explicit]])
Saul is accusing his whole army of acting unfaithfully though this is a generalization because not every soldier acted unfaithfully. (See: [[rc://en/ta/man/translate/figs-hyperbole]])
# Now, roll a big stone here to me
The stone would hold the animals up and make it easier to drain the blood from them. (See: [[rc://en/ta/man/translate/figs-explicit]])
# kill them here, and eat
This would allow Saul to observe if the blood was properly drained from the animals.