In 1513 B.C.E., the nation of Israel experienced a miraculous deliverance from Egyptian bondage and therefore had no reason to doubt those words.
(‏ خروج ٢٠ :‏ ​ ١ ،‏ ٣‏ )‏ وَفِي تِلْكَ ٱلْمُنَاسَبَةِ ،‏ ٱخْتَارَتْ أُمَّةُ إِسْرَائِيلَ أَنْ تُطِيعَ يَهْوَه .‏