Jeremiah 17:10

I the Lord search the heart,.... The inward parts of it, every room and corner in it; and know the thoughts of it; all its intents, purposes, designs, contrivances, and imaginations; all the secret motions of it, and the wickedness that is in it; so that this is an answer to the question in the preceding verse; and therefore, though the heart is deceitful, it cannot deceive him, because he judges not according to outward appearance; he sees and knows the heart; and none but the Lord, or he who is Jehovah, can so search the heart as thus to know it; wherefore, since Christ is said to search the reins and the heart, and to know the thoughts of men, and to be a discerner of the thoughts and intents of the heart, he must be Jehovah, and the true God, Revelation 2:23:

I try the reins; the most inward and remote parts, covered with fat, and out of sight: these are the seat of the affections; and the Lord tries these, whether they are towards him or not; and whether sincere or hypocritical; Christ the omniscient God knew Peter's love to him, and the sincerity of it; for which he appeals to him as such,

John 21:17:

even to give every man accordions to his ways, and according to the fruit of his doings; to do which it is necessary to search the heart, and try the reins, the fountain of all actions; and in which the principles of them are, and according to which they are denominated and judged of: in the future judgment every secret thing will be brought into account; the counsels of the heart will be made manifest; the book of conscience will be opened; and out of it, as well as other books, men will be judged according to their ways and works; and therefore it is requisite that the Judge should be the Lord God omniscient, the searcher and trier of the hearts and reins, as Christ is.