Rashi on Exodus 12:49/רש"י על שמות י״ב:מ״ט

1תורה אחת וגו׳ ONE LAW etc. — This is stated in addition to the similar text in v. 48 in order to declare that the proselyte is equal to the native also in respect to all other commands of the Torah (i. e. the preceding text has reference only to the Paschal offering whilst this is a general statement) (Mekhilta).