Isaiah 6:8: "And I heard the voice of the Lord saying, 'Whom shall I send, and who will go for us?' Then I said, 'Here am I! Send me.'"
Luke 10:2: "And he said to them [the seventy-two He sent out], 'The harvest is plentiful, but the laborers are few. Therefore pray earnestly to the Lord of the harvest to send out laborers into his harvest.'"
Matthew 9:37-38: "37 Then he said to his disciples, 'The harvest is plentiful, but the laborers are few; 38 therefore pray earnestly to the Lord of the harvest to send out laborers into his harvest.'"
Colossians 4:3-4: "3 At the same time, pray also for us, that God may open to us a door for the word, to declare the mystery of Christ, on account of which I am in prison - 4 that I may make it clear, which is how I ought to speak."
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The text is public domain:
1 Hark, the voice of Jesus crying,"Who will go and work today?Fields are white and harvests waiting -Who will bear the sheaves away?"Loud and long the Master calleth;Rich reward He offers thee.Who will answer, gladly saying,"Here am I, send me, send me"?2 If you cannot speak like angels,If you cannot preach like Paul,You can tell the love of Jesus,You can say He died for all.If you cannot rouse the wickedWith the judgement's dread alarms,You can lead the little childrenTo the Savior's waiting arms.3 If you cannot be a watchman,Standing high on Zion's wall,Pointing out the path to heaven,Off'ring life and peace to all,With your prayers and with your bountiesYou can do what God commands;You can be like faithful Aaron,Holding up the prophet's hands.4 Let none hear you idly saying,"There is nothing I can do,"While the multitudes are dyingAnd the Master calls for you.Take the task He gives you gladly,Let His work your pleasure be;Answer quickly when He calleth,"Here am I, send me, send me!"
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Isaiah 6:8 appears in the first verse ("Hark, the voice of Jesus crying, / 'Who will go and work today?'... 'Here am I, send me, send me'") and in the fourth ("'Here am I, send me, send me!'").
The harvest imagery in Luke 10:2 and Matthew 9:37-38 is used in the lines "'Fields are white and harvests waiting - / Who will bear the sheaves away?'" in the first verse, although these lines also borrow from John 4:35: "'Do you not say, "There are yet four months, then comes the harvest"? Look, I tell you, lift up your eyes, and see that the fields are white for harvest.'"
Colossians 4:3-4 seems to be the basis for the second and third verses.
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The lines "You can lead the little children / To the Savior's waiting arms" at the end of the second verse allude to an event recounted in Matthew 19:13-15, Mark 10:13-16, and Luke 18:15-17.
The lines "You can be like faithful Aaron, / Holding up the prophet's hands" at the end of the third verse refer to Exodus 17:11-12: "11 Whenever Moses held up his hand, Israel prevailed, and whenever he lowered his hand, Amalek prevailed. 12 But Moses' hands grew weary, so they took a stone and put it under him, and he sat on it, while Aaron and Hur held up his hands, one on one side, and the other on the other side. So his hands were steady until the going down of the sun."
The lines "Take the task he gives you gladly, / Let His work your pleasure be" in the fourth verse bear some resemblance to 1 Corinthians 7:17 ("Only let each person lead the life that the Lord has assigned to him, and to which God has called him. This is my rule in all the churches.") and Ecclesiastes 3:22 ("So I saw that there is nothing better than that a man should rejoice in his work, for that is his lot. Who can bring him to see what will be after him?").
