מדרש אויף ישעיהו 40:7

"Take up shield and buckler, and rise up to help me." God said to him, "Do I need a shield?" (Psalms 35:2) "Let them be like chaff before the wind, with the angel of the Lord driving them on." I breathe upon them and they wither. Likewise, Isaiah says (Isaiah 40:6), "A voice says, 'Cry!' And I said, 'What shall I cry?' (Isaiah 40:7) 'All people are grass, their constancy is like the flower of the field.'" God said to him, "David, what are you doing?" He said to him, "I praise You." And so it says, "All my bones shall say, 'Lord, who is like You?'" (Psalms 35:10)

"I will thank you, O Lord, with all my heart..." (Psalm 138:1) Isaiah said: "Grass withers and flowers fade, but the word of our God endures forever." (Isaiah 40:8) And what do you have to do on the high mountain? Go up and proclaim the good news to Zion. Israel said: "We are afraid because of our enemies." The Lord said: "Your enemies were but grass. As long as they existed, you were afraid of them. But now that they are gone, lift up your voice and do not be afraid." Israel said: "When will we be able to avenge ourselves against the wicked?" As it is said: "As you have done, it will be done to you; your deeds will return upon your own head." (Obadiah 1:15) What was the punishment for smashing the children of Israel against the rock? As it is said: "Happy is the one who seizes your infants and dashes them against the rocks." (Psalm 137:9) At that time, Israel cursed the Lord with all their heart. As it is said: "I will thank you with all my heart." From this we learn that as long as the wicked are in the world and oppress Israel, pushing them around and not allowing them to curse with all their heart, if they are destroyed at that moment, "I will thank you with all my heart."...

"I will thank you, O Lord, with all my heart..." (Psalm 138:1) Isaiah said: "Grass withers and flowers fade, but the word of our God endures forever." (Isaiah 40:8) And what do you have to do on the high mountain? Go up and proclaim the good news to Zion. Israel said: "We are afraid because of our enemies." The Lord said: "Your enemies were but grass. As long as they existed, you were afraid of them. But now that they are gone, lift up your voice and do not be afraid." Israel said: "When will we be able to avenge ourselves against the wicked?" As it is said: "As you have done, it will be done to you; your deeds will return upon your own head." (Obadiah 1:15) What was the punishment for smashing the children of Israel against the rock? As it is said: "Happy is the one who seizes your infants and dashes them against the rocks." (Psalm 137:9) At that time, Israel cursed the Lord with all their heart. As it is said: "I will thank you with all my heart." From this we learn that as long as the wicked are in the world and oppress Israel, pushing them around and not allowing them to curse with all their heart, if they are destroyed at that moment, "I will thank you with all my heart."...