Rashi on Exodus 16:4/רש"י על שמות ט״ז:ד׳

1דבר יום ביומו THE THING OF THE DAY ON ITS DAY — what is needed for a day’s eating shall they collect on its (that) day, and they shall not today collect what will be needed tomorrow (cf. Mekhilta).

2למען אנסנו הילך בתורתי THAT I MAY TRY THEM WHETHER THEY WILL WALK IN MY LAW — whether they will observe the commands associated with it: viz., that they should not leave any overnight, and that they should not go out on the Sabbath to collect it.