“For with God nothing (rhema) shall be impossible.” (KJV)
“For nothing (rhema) will be impossible with God.” (ESV)
“For no word (rhema) from God will ever fail.” (NIV)
In some Bible translations (ESV and KJV) that translate rhema (4487) as “nothing”, in most other verses, rhema is translated “word.” The translation of rhema to “nothing” gives a nice verse to quote in various situations but is lacking the specificity.
It is more exact to say that God fulfills His every word and even things outside of physical laws are not impossible with Him. But there are some things that are impossible for God, the most obvious being sin (we will not embark on a discussion of other possible self-imposed limitations that came when He gave humans free will).
Specifically, if God has said something, He will not fail to fulfill that thing! (NIV)