Mt 9:36-37, Mt 10:5-6, Mt 15:24
In the Old Testament, God said that the people of Israel were lost under the guidance of false shepherds. (Jeremiah 50:6)
Jeremiah 50:6 My people hath been lost sheep: their shepherds have caused them to go astray, they have turned them away on the mountains: they have gone from mountain to hill, they have forgotten their restingplace.
Jesus lamented that people suffered and were lost like sheep without a shepherd. And Jesus sent his disciples to find these sheep. (Mt 9:36-37, Mt 10:5-6, Mt 15:24)
Mt 9:36 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;
Mt 10:5 These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: 6 But go rather to the lost sheep of the house of Israel.
Mt 15:24 But he answered and said, I am not sent but unto the lost sheep of the house of Israel.