Isaiah 40:11
9 Go up on a high mountain, O herald Zion. Shout out loudly, O herald Jerusalem! Shout, don’t be afraid! Say to the towns of Judah,“Here is your God!” 10 Look, the Sovereign Lord comes as a victorious warrior; his military power establishes his rule. Look, his reward is with him; his prize goes before him. 11 Like a shepherd he tends his flock; he gathers up the lambs with his arm; he carries them close to his heart; he leads the ewes along. 12 Who has measured out the waters in the hollow of his hand, or carefully measured the sky, or carefully weighed the soil of the earth, or weighed the mountains in a balance, or the hills on scales? 13 Who comprehends the mind of the Lord, or gives him instruction as his counselor?
Matthew 18:12
10 “See that you do not disdain one of these little ones. For I tell you that their angels in heaven always see the face of my Father in heaven. 12 What do you think? If someone owns a hundred sheep and one of them goes astray, will he not leave the ninety-nine on the mountains and go look for the one that went astray? 13 And if he finds it, I tell you the truth, he will rejoice more over it than over the ninety-nine that did not go astray. 14 In the same way, your Father in heaven is not willing that one of these little ones be lost. 15 “If your brother sins, go and show him his fault when the two of you are alone. If he listens to you, you have regained your brother.
Notes and References
"... Jesus Built on Jewish Images ... Second Isaiah pictured God as the Shepherd of Israel, tenderly caring and nurturing His people. "He will pasture His flock like a shepherd. He will gather the lambs in His arms and carry them in His bosom." Ezekiel painted the same image. "Thus says the Lord God: Behold, I Myself will search for my sheep and will seek them out. As a shepherd seeks out his flock when some of his sheep have gotten separated, so will I seek out My sheep .... I will pasture them on the mountains of Israel, by the water-courses and in all the settled places of the land." That was Luke's understanding also. God was the Shepherd, and heaven rejoiced at the redemption of the soul who strayed. While the nature of the straying is vague in Matthew, in Luke it was clear. People who sin are like sheep that lost their way and needed to be rescued. God rejoiced in the salvation of every sinner ..."
Stern, Frank A Rabbi Looks at Jesus’ Parables (p. 125) Rowman & Littlefield Publishers, 2006