# Though the mountains may fall and the hills be shaken, yet my steadfast love will not ... be shaken

"Even if the mountains were to fall and the hills were to shake, my steadfast love will not ... be shaken"

# the hills be shaken

"the hills may shake" 

# my steadfast love will not turn away from you

"I will not stop loving you" 

# nor will my covenant of peace be shaken

"and I will not cancel my covenant of peace" or "and I will surely give you peace as I promised in my covenant" 

# says Yahweh, who has mercy on you

"that is what I, Yahweh, who acts mercifully, say"