וְאֵ֖ת שְׁנֵ֣י בָנֶ֑יהָ אֲשֶׁ֨ר שֵׁ֤ם הָֽאֶחָד֙ גֵּֽרְשֹׁ֔ם כִּ֣י אָמַ֔ר גֵּ֣ר הָיִ֔יתִי בְּאֶ֖רֶץ נָכְרִיָּֽה׃
그 두 아들을 데렸으니 그 하나의 이름은 게르솜이라 이는 모세가 이르기를 내가 이방에서 객이 되었다 함이요
Chizkuni
גר הייתי, “I had been a stranger, etc.” the word הייתי is not to be understood as being in the past tense, just as Genesis 23,13: נתתי or 14,22 הרימותי or 32,11 הייתי לשני מחנות are not to be understood as being in the past tense. There are many more such examples.
Ramban
AND HER TWO SONS; OF WHOM THE NAME OF THE ONE WAS GERSHOM. Even though this is not the place where [the narrative of] their birth is told, Scripture here explains the names of the two sons [of Moses — Gershom and Eliezer —] because there was no opportunity to mention the name of Eliezer at his birth, as I have explained in Seder V’eileh Shemoth.61Above, 4:20. See Ramban there regarding why Eliezer was not named at that time. Gershom’s name, on the other hand, is mentioned in 2:22. Here, Scripture wanted to mention the kindness that the Holy One, blessed be He, had shown to Moses, who was a stranger in a strange land. [When he named his second son], he gave thanks there to G-d for having delivered him from the sword of Pharaoh when he fled from before him,62Ibid., 2:15. [and for making him] now king over Israel, and [because] He drowned Pharaoh and his people in the sea.
The sense of the expression for he said, I have been a stranger, etc. is connected with Moses, who is mentioned in the first verse, [and not with Jethro, who is mentioned in the second verse]. Similarly, the following verse, And the name of the other was Eliezer: for the G-d of my father was my help,63Verse 4. is connected with the expression for he said, [found in the verse before us. It thus reads: “And the name of the other was Eliezer; for he said: for the G-d, etc.”] There are many cases like that.
The sense of the expression for he said, I have been a stranger, etc. is connected with Moses, who is mentioned in the first verse, [and not with Jethro, who is mentioned in the second verse]. Similarly, the following verse, And the name of the other was Eliezer: for the G-d of my father was my help,63Verse 4. is connected with the expression for he said, [found in the verse before us. It thus reads: “And the name of the other was Eliezer; for he said: for the G-d, etc.”] There are many cases like that.
Or HaChaim
שם האחד גרשם, the name of the one was Gershom, etc. Although the reason Moses named this son Gershom has already been mentioned in Exodus 2,22, it had to be repeated here in order to inform us that we are talking about the same son already mentioned in chapter 2 (though this may have been 60 years earlier) and not another son (by the same name but born of a different mother).