Numbers 9:14

וכי יגור אתכם גר ועשה פסח AND IF A STRANGER SHALL SOJOURN AMONG YOU, AND WILL KEEP THE PASSOVER [ACCORDING TO THE ORDINANCE OF THE PASSOVER … SO SHALL HE DO] — One might think that this verse implies that anyone who becomes a proselyte (גר) must keep the Passover offering rite immediately after his circumcision (even though it has not taken place just before Passover), therefore Scripture states, “yo shall have one ordinance, [both for the stranger, and for him that was born in the land]” (which implies that just as the native brings the offering on the fourteenth of Nisan, so the proselyte, too, must bring it only on the fourteenth of Nisan; cf. Rashi on Exodus 12:48). What the first part of the verse implies is, therefore, the following: “and if a proselyte will sojourn among you, and comes to celebrate the Passover rite together with his fellows, then according to the ordinance of the Passover and according to the manner thereof shall he do” (i.e. ועשה פסח is not a predicative clause — when he becomes a proselyte then shall he offer the Passover, i. e. offer it immediately — but it is a conditional clause, coordinate to וכי יגור אתכם and the apodosis begins with כחקת הפסח etc.) (Sifrei Bamidbar 71).

וְכִֽי־יָג֨וּר אִתְּכֶ֜ם גֵּ֗ר וְעָ֤שָֽׂה פֶ֙סַח֙ לַֽיהֹוָ֔ה כְּחֻקַּ֥ת הַפֶּ֛סַח וּכְמִשְׁפָּט֖וֹ כֵּ֣ן יַעֲשֶׂ֑ה חֻקָּ֤ה אַחַת֙ יִהְיֶ֣ה לָכֶ֔ם וְלַגֵּ֖ר וּלְאֶזְרַ֥ח הָאָֽרֶץ׃ {ס}        

And if a stranger shall sojourn among you, and will keep the passover to the Lord; according to the ordinance of the passover, and according to its prescribed manner, so shall he do: you shall have one ordinance, both for the stranger, and for him that was born in the land.