The correct spelling is "וירעם" and it means "and his heart trembled". Rabbi Abbahu said in the name of Rabbi Yochanan that one should sit and contemplate so that he will not take a turn guarding with his friend in the field. Rabbi Yudan Meshkalisa said that David sang to God with all kinds of instruments, what does it say in the end? "Let the praise of God be in their throats, and a two-edged sword in their hands" (Psalm 149:6), this refers to God's instrument, the sword.
A Psalm of Asaph. God, nations have come into Your inheritance; they have defiled Your holy temple, they have laid Jerusalem in ruins. This is what the Scripture says (Lamentations 4:12), "The kings of the earth did not believe, nor all the inhabitants of the world, that the adversary and the enemy could enter the gates of Jerusalem." Who would have believed that Jerusalem would be conquered by its enemies, after all the miracles that occurred during the days of King Hezekiah, when Sennacherib besieged the city? When a group of Amalekites attacked Ziklag, burned it down, and took everything in it captive, David and his men were heartbroken. David asked the Lord (1 Samuel 30:8), "Shall I pursue after this troop? shall I overtake them?" And he answered him, "Pursue: for thou shalt surely overtake them, and without fail recover all." David did as he was told and found the Amalekites, and he smote them from the twilight even unto the evening of the next day. What did the Lord do? (2 Chronicles 14:11) "And the Lord smote the Cushites before Asa." Jehoshaphat stood and said, "Master of the Universe, I have no strength to chase after them and make war with them, but we will stand here and You pursue them." And so the Lord did, as it says (2 Chronicles 20:22), "And when they began to sing and praise, the Lord set ambushments against the children of Ammon." What did the Lord do? He dressed them up in shining garments in Alexandria, and they saw each other. Hezekiah stood at the time when Sennacherib came and said, "I have no strength to chase or see the war, but when I sleep on my bed, You fight for us." The Lord said, "I will do so; you sleep on your bed and I will fight for you," as it says (2 Samuel 19:35), "And it came to pass that night, that the Lord smote the camp of the Assyrians." And they went up from them and from all these inhabitants, one hundred and eighty-five thousand, all officers and nobles, except for their inhabitants. Our Rabbis said, only those who are mentioned in Isaiah 8:8, "And he shall pass through Judah; he shall overflow and go over, he shall reach even to the neck; and the stretching out of his wings shall fill the breadth of thy land, O Immanuel," were spared. And the wingspan of one rooster is sixty, and all those [Assyrians] died. And how many were spared from them? Rav said ten, as it says (Isaiah 10:19), "And the young man shall lead them." And how many does a young man write? Ten. So, ten were spared from them. Rabbi Eliezer says six were spared from them, and how many does a young man write? Six. Rabbi Yehudah says five were spared from them, as it says (Isaiah 17:6), "And there shall be left therein gleanings, as when the olive tree is beaten, two or three berries in the top of the uppermost bough, four or five in the outermost branches of a fruitful tree, saith the Lord God of Israel." So, five were spared from them. Rabbi Tanchum bar Chiyya says nine were spared from them, as it says (Isaiah 10:19), "And the rest of the trees of his forest shall be few, that a child may write them." "Nine remained of them. Rabbi Tanhum says fourteen. Two or three, behold there are five. Four and five, behold there are nine. Nebuchadnezzar was one of them, as when the people of Jerusalem angered the Lord, He sought to bring up Nebuchadnezzar to destroy Jerusalem and exile Israel from the land, as it is said: 'Behold, I will send Nebuchadnezzar, My servant, and he shall lay waste to Jerusalem and its inhabitants' (Jeremiah 25:9). Rabbi Levi said that for eighteen years a heavenly voice was heard in the house of that wicked man, Obadiah b. Ishmael, but the people of his city would not listen to him. He was afraid to go up [to heaven], for he knew what had befallen Sennacherib in the days of Hezekiah, and he did not believe that the Lord would destroy Jerusalem, as it is said: 'The kings of the earth did not believe' (Lamentations 4:12). What did he do? He stood a divination charm to find out whether to go up or not, as it is said: 'For the king of Babylon stood at the parting of the way, at the head of the two ways, to use divination' (Ezekiel 21:26). He would throw an arrow to Antioch or to Tyre or to Lod, and the arrow would break. But when he would throw it towards Jerusalem, it would not break, and he knew that it was destroyed. When he saw this, he began to say before the Lord, 'Master of the universe, who would have believed that the haters would enter Jerusalem and destroy it, a place over which Your hand had not reigned? Behold, I see that they have entered and defiled Your sanctuary and scattered Your children among the nations in Your inheritance. Woe, for the kings of the earth did not believe!'"