Ibn Ezra on Numbers 15:16

וטעם תורה אחת. לבד מהעולות כי העולות הם בחיוב חקה ועוד אמר השם כאשר תביאו מנחה על העולה מהסלת כן תתנו גם מעריסותיכם ואין צורך להזכיר מה שקבלו קדמונינו ז"ל כי הם שתים חלה ותרומה ושיעורן לפי שכל דבריהם אמת וזולתם הבל הנה שעור נוסף בין שעשו בשגגה מה שצוו שלא לעשות ובין שלא עשו בשגגה מה שצוו לעשות: [ONE LAW.] Its meaning is, one law aside from the burnt offerings, for the burnt offerings are obligated by statute.³³For that is what the word chukkah (statute) refers to. Verse 15 states, there shall be one statute (chukkah) both for you, and for the stranger that sojourneth with you. Verse 16 states, One law (Torah) and one ordinance shall be both for you, and for the stranger. Prima facie, Scripture is redundant. Hence I.E. comments that verse 15 deals with that which is obligatory, namely, the burnt offering (for it concludes the law mentioned in verse 14, which deals with sacrifices), and verse 16 deals with all the other commandments, for it speaks of Torah (Filwarg). God also says,³⁴In verses 19-21. as you bring a meal offering of fine flour along with the burnt offering, thus shall you do with your dough.³⁵One must set aside a portion of one’s dough as a gift unto God. Hence the law of hallah follows the law of the meal offering. There is no need to mention what our ancients, of blessed memory, received by tradition, namely, that one is obligated to set aside two offerings, a portion of the dough³⁶Hallah. and a portion of the grain,³⁷Terumah. In other words, one has to set aside a portion from the dough, even though he has already set aside a portion from the grain out of which this very dough was made (Filwarg). and their amount.³⁸How much one has to set aside. Their words are true. Everything else is nonsense.