Or HaChaim on Exodus 5:1/אור החיים על שמות ה׳:א׳

1 ואחר באו משה ואהרון ויאמרו אל פרעה, afterwards Moses and Aaron came to Pharaoh and said, etc. The word "afterwards" means after the people had believed that G'd had despatched Moses to them as their redeemer. The verse refers to fulfilment of what G'd had told Moses in 3,18. We now appreciate the dividing tone sign etnachta under the word לקולך in 3,18; we would have expected the words "and you will proceed to Pharaoh" to be part of the same sequence. Inasmuch as some considerable time passed between what was mentioned in the first half of that verse and the completion of what it was meant to lead to, the Torah repeats here that now the second part of verse 18 in chapter 3 was being played out.