Rashi on Genesis 15:1/רש"י על בראשית ט״ו:א׳

1אחר הדברים האלה — Wherever the term אחר is used it signifies immediately after the preceding event; whilst אחרי signifies a long time afterwards. אחר הדברים האלה AFTER THESE THINGS means: after this miracle has been wrought for him in that he slew the kings and he was in great anxiety, saying, “Perhaps I have already received, in this God-given victory reward for all my good deeds” — therefore the Omnipresent said to him, אל תירא אברם אנכי מגן לך FEAR NOT ABRAM, I AM THY SHIELD against punishment: for you shall not be punished on account of all these people whom you have slain. And as for your being anxious regarding the receipt of any further reward, know that שכרך הרבה מאד THY REWARD WILL BE EXCEEDING GREAT (Genesis Rabbah 44:5).