`Umar went to Sham and when he reached Sargh, he got the news that an epidemic (of plague) had broken out in Sham. `Abdur-Rahman bin `Auf told him that Allah’s Messenger (ﷺ) said, “If you hear that it (plague) has broken out in a land, do not go to it; but if it breaks out in a land where you are present, do not go out escaping from it.”
I got (my head) shaved before sacrificing the, animal, whereupon be (the Holy Prophet) said: Sacrifice the animal (now) ; there is no harm in it. He (the person said): I sacripced the animal before throwingpebbles. whereupon he said: Throw pebbles (now) ; there is no harm in it.