Book of Hosea Chapter 2 Vs. 20

 The Lord's Mercy on Israel

I will even betroth thee unto me in faithfulness: and thou shalt know the LORD. Hos. 2:20

I will even... And it is he that makes them faithful unto him, and gives them faith to believe in him, receive, embrace, own, and acknowledge him as their husband: and in this sense, some understand it, rendering it, "in faith".

This is the third time the word "betroth" is used, or this promise made; which, according to Jerome, refers to them espousing of the Jews in Abraham, at Mount Sinai, and in the times of Christ.

Keeping the marriage contract inviolable, Christ will never suffer his faithfulness to fail, nor break his covenant. As he is faithful to his Father that appointed him, so he is, and will be, to his church and people, and to every believer, to whom he is espoused.

and thou shalt... That the Messiah is Jehovah, and that he is their husband; they shall all know him, from the least to the greatest; they shall have a saving knowledge of him, which will issue in eternal life; they shall own him, and acknowledge him, serve and obey him, as their Lord, Head, and Husband, as well as love him, and believe in him.

Hebrews 8:11 "And they shall not teach every man his neighbor, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest."

thou shalt know... This is very characteristic of Ezekiel who uses such an idea about 75 times, compared to this once in Hosea.

This knowing is a free gift from God.

In response to the divine love showered on her, Israel will acknowledge the Lord. In contrast with her former tendency to forget (cf. Hos. 2:13) she will recognize His authority by demonstrating loyalty to Him. “Acknowledge” (yāḏa‛, “to know”) often occurs in covenantal contexts with the sense of “recognize.” For example, the Lord recognized (lit., “knew”) Israel’s special relationship to Him (cf. Amos 3:2 1, KJV). Israel in return was to recognize (lit., “know”) only the authority of her Lord (cf. Hos. 13:4). In Hebrew thought, such recognition was not a mere mental exercise; it implied action (cf. Jer. 22:16). In Israel’s case it meant obedience to the Lord’s commandments (cf. Hos. 8:1-2). In the future all Israel will “know” the Lord because, as Jeremiah wrote, He will put His “Law in their minds and write it on their hearts” (Jer. 31:33). This is the promise of the New Covenant (Jer. 31:31-34), which corresponds to the new marriage pictured in Hos. 2:19-20.