Can you claim what you don’t know of? I suppose not, and so akin to claiming a promise is knowing the promise and understanding every detail of the promise.
As we continue to follow the journey of the Israelites under the leadership of Joshua, we see how Caleb (in Joshua 14) shows full understanding of the promise made to him and he confidently claims what has been promised to him.
He definitely also did his part as he remained in ‘whole obedience’ to God at all times. There will always be a role which we all have to play in receiving God’s promises to us. Let us know His promises and let us play our part.