'Join' in the Bible

He sent this message to King Jehoshaphat of Judah: "The king of Moab has rebelled against me. Will you fight with me against Moab?" Jehoshaphat replied, "I will join you in the campaign; my army and horses are at your disposal."

Later on, King Pul of Aram attacked the land, and Menahem paid Pul 1,000 silver talents so Pul would join forces with Menahem to secure his hold on the kingdom.

The king stood by the pillar and made a covenant before the Lord, to walk after the Lord and to keep His commandments, His testimonies, and His statutes with all his heart and soul, to confirm the words of this covenant that were written in this book. And all the people entered into the covenant.