“Yahweh says.
‘Yet even now!
Return to me!
With all your heart!
Return with fasting!
Return with weeping!
Return with mourning!
Rend your hearts!
Not your garments!’”
Joel has Yahweh speak directly in the first-person singular. Yahweh himself wanted them to return to him, with all their hearts, after this devastating plague of locusts has hit them. They were to return to Yahweh by fasting, weeping, and mourning. They were to break open their hearts, and not tear their garments.
Eugene Finnegan Bible Project 