Isaiah 49:23 - Matthew Poole's English Annotations on the Holy Bible

Kings shall be thy nursing fathers, and their queens thy nursing mothers; kings and queens shall have a sincere affection and tender regard unto thee and thy children, which was in some sort fulfilled by Cyrus, Ahasuerus, and some few others of the Persian kings or queens, but much more truly and fully by those many kings and emperors of the Gentile world, which after Christ's time did both themselves embrace the true religion, and also set it up in their several dominions. They shall bow down to thee with their face toward the earth, and lick up the dust of thy feet; they shall highly reverence and honour thee, and shall most humbly and readily submit themselves unto thee, which was not verified in any of the Persian kings, but only in these kings who were converted to the Christian faith and church. The expressions are borrowed from the practice of the Eastern people in their prostrations and adorations, when they bowed so low as to touch and kiss the ground, whereby they did or might seem to lick up the very dust of the ground which was about or under the feet of those whom they adored. They shall not be ashamed that wait for me; their hopes and expectations shall not be disappointed, but abundantly satisfied.