'Firmly' in the Bible

Now it will come to pass thatIn the last daysThe mountain of the house of the LordWill be [firmly] established as the highest of the mountains,And will be exalted above the hills;And all the nations will stream to it.

Indeed this is what the Lord told me. He took hold of me firmly and warned me not to act like these people:

‘Behold, the Lord is about to hurl you headlong, O man.And He is about to grasp you firmly

and I will clothe him [with] your tunic, and I will bind your sash firmly about him, and I will put your authority into his hand, and he shall be like a father to the inhabitants of Jerusalem and to the house of Judah.

therefore this is what the LORD God says: "Look! I am laying a foundation stone in Zion, a tested stone, a precious cornerstone for a sure foundation: Whoever believes firmly will not act hastily.

Your tackle hangs slack;It cannot hold the base of its mast firmly,Nor spread out the sail.Then the prey of an abundant spoil will be divided;The lame will take the plunder.

For the Lord says this:“For the eunuchs who keep My Sabbaths,and choose what pleases Me,and hold firmly to My covenant,

And the foreigners who join themselves to the Lordminister to Him, love the name of Yahwehand become His servants,all who keep the Sabbath without desecrating itand who hold firmly to My covenant—