labor to preach the gospel

Matthew 9:36-38

36 But when he saw the multitudes, he was moved with compassion on them, because they fainted, and were scattered abroad, as sheep having no shepherd. 37 Then saith he unto his disciples, The harvest truly is plenteous, but the labourers are few; 38 Pray ye therefore the Lord of the harvest, that he will send forth labourers into his harvest.

Mark 16:15

And He said to them, "Go into all the world and preach the gospel to every creature