'Know' in the Bible

Therefore, I will always be ready to remind you of these things, even though you already know them and are established in the truth which is held firmly in your grasp.

knowing that the laying aside of this earthly tent of mine is imminent, as our Lord Jesus Christ has made clear to me.

First of all, know [without any doubt] that mockers will come in the last days with their mocking, following after their own human desires