Numbers 23:19 [NLT], God is not a man, so he does not lie.  He is not human, so he does not change his mind.  Has he ever spoken and failed to act?  Has he ever promised and not carried it through?

Romans 4:20-21 [NASB], "yet, with respect to the promise of God, he did not waver in unbelief but grew strong in faith, giving glory to God, 21 and being fully assured [persuaded] that what God had promised, He was able also to perform."

"An anchor is only as secure as that to which it is fastened to."   

Hebrews 6:19-20 [NASB], "This hope we have as an anchor of the soul, a hope both sure and steadfast and one which enters within the veil, 20 where Jesus has entered as a forerunner for us..."