Yechezkel 33:3

3 If when he seeth the cherev come upon HaAretz, he blow the shofar, and warn HaAm;

Yechezkel 33:3 Meaning and Commentary

Ezekiel 33:3

If what he seeth the sword come upon the land
Or those that kill with the sword, as the Targum; as soon as he observes a body of armed men, more or less, marching towards the borders of the land with a manifest intention to enter and invade it: he blow the trumpet, and warn the people;
warn the people by blowing the trumpet, the signal agreed on; by which they would understand that an enemy was at hand, or danger near; or warn them by word of mouth, as well as by the trumpet, where he could do it, and when it was necessary.

Yechezkel 33:3 In-Context

1 3 Again the Devar Hashem came unto me, saying,

2 Ben Adam, speak to the Bnei Amecha, and say unto them, When I bring the cherev upon eretz, if the Am HaAretz take ish echad (one man) within their midst, and appoint him for their tzofeh (watchman, sentinel),

3 If when he seeth the cherev come upon HaAretz, he blow the shofar, and warn HaAm;

4 Then whosoever heareth the sound of the shofar, and taketh not warning; if the cherev come, and take him away, his dahm shall be upon his own rosh.

5 He heard the sound of the shofar, and took not warning; his dahm shall be upon him. But he that taketh warning shall save his nefesh.