Rashi on Exodus 3:18/רש"י על שמות ג׳:י״ח

1ושמעו לקלך AND THEY SHALL HEARKEN TO THY VOICE — as soon as you will mention to them this expression (the double use of the verb פקד as in v. 16) they will hearken to your voice, for they have long had this sign as a tradition from Jacob and Joseph that by mention of this phrase their deliverance will be brought about. Jacob said to them “And God will surely visit you”, and Joseph said to them (Genesis 50:25) “God will surely visit you”.

2נקרה עלינו GOD HATH HAPPENED TO MEET US — The word נקרה signifies a casual meeting. Similar are: (Numbers 23:4) “And God happened to meet (ויקר) [Balaam]”; (Numbers 23:15) ואנכי אִקָּרָה כה which means “I will be met by him yonder”.