Isaiah 49:23

And kings shall be thy nursing fathers, and their queens thy nursing mothers,.... Who shall show favour and respect to the church and people of God, grant them liberty, and protect and defend them in their religious privileges: for this is to be understood not figuratively of apostles and apostolical men, as Jerom, who are kings and priests unto God, and who feed the church with the milk of the word, and the breasts of ordinances; but literally of the kings and queens of the earth; and is thought to have had its fulfilment, at least in part, in Cyrus, Ahasuerus, Esther, and others; but more so in Christian kings and queens, as Constantine and Helena, Theodosius and Placilla, and others; and will have a far greater accomplishment in the latter day glory; see Isaiah 60:3:

they shall bow down toward thee with their faces toward the earth; which expresses the great veneration and respect these great personages shall have for the church of God, and their entire submission and subjection to the Gospel of Christ, and the ordinances of it, and to the laws and discipline of his house; for they shall now become members of the Christian church, and be entirely under the government of it, as to religious things; see Revelation 3:9

and lick up the dust of thy feet; the allusion is to the eastern nations, especially the Persians, who, in the adoration of their kings, used to kiss the ground they stood on, and seemed to lick, if they did not, the dust that was about them; and it expresses the very low submission of kings and princes to the church, and their high veneration of it; their willingness to do the meanest office for the good of it, and their great regard and affection for the meanest of its members, the dust of Zion; see Psalms 72:9:

and thou shalt know that I am the Lord; the King of kings, and Lord of lords, who has the hearts of all men, even of kings, in his hands, and can turn them, and bring them to a thorough submission to his will; and who is able to accomplish all his promises, and is true and faithful to them; this will be known and owned by the church, when the above things have their accomplishment:

for they shall not be ashamed that wait for me; or for my salvation, as the Targum; for favours from him; for the light of his countenance; for the discoveries and application of pardoning grace; for the performance of promises; for answers of prayer; for his spiritual coming, and for eternal glory and happiness; these shall not be ashamed of him for whom they wait, nor of their hope and expectation of him, nor at his coming.