he said i shall never send him with you until you give me an oath upon allah that you will bring him back to me unless you are surrounded and when they gave him their oath that allahs guarantee is upon what we say. 
قال لن أرسله معكم حتى تؤتون موثقا من الله لتأتنني به إلا أن يحاط بكم فلما آتوه موثقهم قال الله على ما نقول وكيل