“I have set watchmen upon thy walls, O Jerusalem, which shall never hold their peace day nor night: ye that make mention of the LORD, keep not silence, and give Him no rest, till he establish, and till he make Jerusalem a praise in the earth.” Isaiah 62:6-7 (KJV)
The prophet, speaking for the LORD makes mention of “Watchmen”. There were men set to guard the city, watching for an approaching enemy, and shouting out warning, or blowing the warning sound.
This is a call of the remnant of God to be strong in the LORD, His faith, His word, and to be faithful to Him; and to pray. Pray even to reminding God of His promises to Israel. To do so as though they were giving God no rest.
It seems that is what diligent, fervent prayer is really. Just for a side note. Prayer is for the people of God. Faith also is not a power of its own; but of God, and in God alone. God, the LORD, the Creator of all that is; also the Father, Son, and Holy Spirit of the Godhead.
The watchmen are the preachers, the prophets, the priests of God who still cherish the LORD God, His word, His work, and His will. These will proclaim the word of God without fear, favor, or compromise calling God’s people to repentance and faith in Him. They also will get a hold of God in prayer and never let Him go, reminding Him of His promises; though He never forgets them.
The power of prayer is through the faith of the crucified Lord Jesus Christ, His burial, and resurrection. He is the Son of God, God the Son. The God Man.