Hebrews 6:15-16 (NKJV)
"And so, after he had patiently endured, he obtained the promise. For men indeed swear by the greater, and an oath for confirmation is for them an end of all dispute."
Hebrews 6:15-16 (MSG)
"Abraham stuck it out and got everything that had been promised to him. When people make promises, they guarantee them by appeal to some authority above them so that if there is any question that they’ll make good on the promise, the authority will back them up."
To call into question or cast doubt upon, To question the truth or validity of; doubt.
2 Timothy 2:13 (AMP)
"If we are faithless [do not believe and are untrue to Him], He remains true (faithful to His Word and His righteous character), for He cannot deny Himself."