Isaiah 44:5
One shall say, I am the LORD’s; and another shall call himself by the name of Jacob; and another shall subscribe with his hand unto the LORD, and surname himself by the name of Israel. One shall say, I am the LORD’s; and another shall call himself by the name of Jacob; and another shall subscribe with his hand unto the LORD, and surname himself by the name of Israel.
Isaiah 44:5 stands in Isaiah 41-45 where God fully reveals His purpose for His people, a portion to be prayerfully studied, and that purpose is for His people to look to Him and not to turn away from Him to finite human beings for wisdom. It belongs among God's promises and covenant commitments in Isaiah 44 and the surrounding chapters, which show what He has done and will do for those who press on to know Him. Those promises call His people to recognize and value what He has covenanted to do for them.
Its immediate setting is His promise to Jacob His servant and to Israel and Jeshurun whom He chose, made and formed from the womb and will help. He promises to pour water on the thirsty and floods on dry ground and to pour His Spirit on their descendants and His blessing on their offspring so they spring up like grass and like willows by the watercourses. At the same time the Lord as King of Israel and Redeemer and Lord of hosts declares that He is the first and the last with no God beside Him and calls His witnesses not to fear.
The verse means that people openly declare that they belong to the Lord and identify themselves with Jacob and Israel by taking those names as their own and subscribing themselves to the Lord. Those who make this identification include people from the nations who hunger and thirst for righteousness, who join themselves to God and are numbered among God's people as spiritual Israel. The verse also describes what happens when God pours out His Spirit and blessing on the next generation, as children raised in truth and righteousness grow into a people who belong to Him and publicly confess that belonging.
In its surrounding account of God's purpose, Jacob and Israel are His servants whom He has redeemed and whose sins He has blotted out, whom He calls to return to Him, and in whom He is glorified. This open declaration of belonging rests on being bought with an infinite price, so that soul, body and spirit belong to Jesus Christ and are not one's own. It is to be made in humility yet with firmness and decision as a commitment to serve Him with all heart, mind, might and strength. The verse belongs to looking to Jesus for spiritual knowledge, so that the light is not hidden but gives light to all in the house, in keeping with God giving His Son as a light to open blind eyes and bring prisoners out of darkness. The thirsty people all around who need to be refreshed and restored are those to whom the Lord declares His purpose to pour water on the thirsty, which is highly relevant where a health institution is full and a city remains unworked and many lack knowledge of how to care for themselves.