Exodus 13:11

והיה כי יביאך AND IT SHALL COME TO PASS WHEN [THE LORD] SHALL BRING THEE … [THOU SHALT SET APART etc.] — There are some of our Rabbis who learned from this statement that the firstborn who were born in the wilderness were not thus hallowed. He who says that these were thus hallowed explains this “coming” (i. e. this verse, which appears to make the hallowing of the firstborn dependent upon their arrival in the land) as follows: if you observe it (this command) in the wilderness, you will be privileged to enter the land and to observe it there (cf. Bekhorot 4b). נשבע לך HE SWORE UNTO THEE — And where did He swear this unto thee? (Exodus 6:8) “And I will bring you unto the land concerning which I did lift up my hand etc.” (cf. Rashi on this verse where he explains that “lifting up the hand” denotes taking an oath) (Mekhilta). ונתנה לך AND SHALL GIVE IT TO THEE Let it be in thine eyes (regard it) as though He had given it to thee on that same day (when on each occasion you carry out this command) and do not regard it as an inheritance from your ancestors (Mekhilta).

וְהָיָ֞ה כִּֽי־יְבִאֲךָ֤ יְהֹוָה֙ אֶל־אֶ֣רֶץ הַֽכְּנַעֲנִ֔י כַּאֲשֶׁ֛ר נִשְׁבַּ֥ע לְךָ֖ וְלַֽאֲבֹתֶ֑יךָ וּנְתָנָ֖הּ לָֽךְ׃

And it shall be when the Lord shall bring thee into the land of the Kena῾ani, as he swore to thee and to thy fathers, and shall give it thee,