Book of Hosea Chapter 2 Vs. 15

 The Lord's Mercy on Israel

And I will give her her vineyards from thence, and the valley of Achor for a door of hope: and she shall sing there, as in the days of her youth, and as in the day when she came up out of the land of Egypt. Hos. 2:15

The valley of... (“Valley of Trouble”), was where Achan disobeyed God and kept the enemy’s plunder, resulting in great devastation for the Israelites (Joshua chapter 7). Yet God promised to turn this valley into “a door of hope” for His people. He does this for all His children who actively seek the hope He has provided (Rev. 3:20).

God's forgiveness is not just in words, He restores her vineyards again. He pours out His blessings on her again.

a door of... There is hope. Just as God was the hope of the family of Jacob in Egypt, He is the hope of the Israelite's here. Achor is not very far from the fertile land of Jericho. Achor is the entrance to that land. In Jericho today, the fruit and vegetables are far more than they need for themselves. It is so fruitful that they sell much of it. This is a prosperous area.

When the Lord leads Israel out of the desert back into the Promised Land, He will restore her vineyards. The words There I will give misinterpret the elliptical Hebrew text (which reads lit., “from there”) by implying that vineyards will grow in the wilderness where Israel had wandered. The agricultural prosperity envisioned here will be in Israel (cf. Hos. 2:22-23; Deut. 30:4-5, 30:9; Amos 9:13-15), not in the desert. When Israel enters the land she will again pass through the Valley of Achor (lit., “Valley of trouble”), the site of Achan’s heinous sin which jeopardized the success of the Conquest (Jos. 7:1-26). However, this time the valley will be a symbol of better things to come, a door of hope leading to repossession of the Promised Land (cf. Isa. 65:10). The effects of the trouble caused by Israel’s past unfaithfulness will have disappeared. Instead she will respond favorably to the Lord as in the days immediately after the Exodus (cf. Jer. 2:2). Admittedly this earlier period is idealized here, as even a cursory reading of the narratives in Exodus and Numbers reveals.