Ibn Ezra on Numbers 16:1

ויקח קרח. זה הדבר היה במדבר סיני כאשר נתחלפו הבכורים ונבדלו הלוים כי חשבו ישראל שמשה אדונינו עשה מדעתו לתת גדולה לאחיו גם לבני קהת שהם קרובים אליו ולכל בני לוי שהם ממשפחתו והלוים קשרו עליו בעבור היותם נתונים לאהרן ולבניו וקשר דתן ואבירם בעבור שהסיר הבכורה מראובן אביהם ונתנה ליוסף אולי חשדוהו בעבור יהושע משרתו גם קרח בכור היה כי כן כתוב. ודגל ראובן חונה בנגב וקרח בנגב המשכן כי הוא מבני קהת ואלה נשיאי העדה היו בכורים והם היו מקריבים את העולות על כן לקחו מחתות והראיה על זה הפירוש מופת המטה שראו כל ישראל כי השם בחר שבט לוי תחת הבכורים על כן כתוב ותכל תלונתם כי התלונה על זה היתה. גם אמר משה כי לא מלבי בעבור שחשדוהו כי מלבו עשה ועוד לא ה' שלחני בשליחות הזה כי כבר האמינו בו כל ישראל ועוד ראיה גמורה כי כל העדה כלם קדושים וזה רמז לבכורים שהם קדושים כי כן כתוב קדש לי כל בכור והם היו הכהנים הנגשים אל ה' והם עיקר כל העדה: NOW KORAH, THE SON OF IZHAR…TOOK. This event occurred in the wilderness of Sinai when the first-born were set aside¹From serving as priests. and the Levites were placed in their stead.²See I.E. on Ex. 32:29 (Vol. 1, p. 680). Israel thought that our master Moses acted out of his own will in giving his brother an elevated position. They suspected that he acted similarly towards the sons of Kohath, who were his relatives, and to all the sons of Levi who were of his family. The Levites rebelled against Moses because they were subservient to Aaron and his sons. Dathan and Abiram rebelled because Moses³Actually Jacob did so on his death bed. However, Moses enforced Jacob’s decree. Hence Dathan and Abiram blamed Moses. removed the birthright from Reuben their forefather, and gave it to Joseph. It is also possible that they suspected that Moses favored the tribe of Joseph because Joshua was his assistant.⁴Joshua was descended from Ephraim the son of Joseph. Korah too was a first-born, as Scripture clearly states.⁵Ex. 6:21. The banner of Reuben camped in the south.⁶Num. 2:10. So did Korah, for he was a Kohathite.⁷The family of Kohath camped south of the tabernacle. See Num. 3:29. Thus these two disgruntled factions camped next to each other. Their proximity facilitated their rebellion. The princes of the congregation were first-born. They offered the burnt offering. They therefore took the fire pans. The miracle of the staff,⁸The blossoming of the staff of Levi. See Num. 17:23. which demonstrated to all of Israel that God chose the Levites in place of the first-born, is proof that this explanation is correct.⁹That the rebellion was triggered by the rejection of the first-born, for otherwise why demonstrate that God chose the Levites. Hence Scripture reads, that there may be made an end of their murmurings against Me (Num. 17:25), for the murmuring was an account of this.¹⁰The substitution of the Levites for the first-born. Moses also said, that I have not done them of mine own mind (v. 28). He said the aforementioned because Israel had come to believe that he had acted on his own. Furthermore, Moses said, then the Lord hath not sent me (v. 29) in this thing,¹¹To have the kohanim take the place of the first-born and the Levites be subservient to the kohanim. because Israel had come to believe in him.¹²That Moses acted in accordance with God’s command in all other things. “In this thing” is part of I.E.’s interpretation of the Lord hath not sent me. It does not appear in the verse. Here is another rigorous proof: seeing all the congregation are holy (v. 3). The aforementioned alludes to the first-born who are holy, for Scripture states, Sanctify unto Me all the first-born (Ex. 13:2). The first-born were the priests that come near to the Lord (Ex. 19:22). They were the most important ones of the congregation.

ויקח קרח. אנשים דרך קצרה כמו חמור לחם ורבים ככה ויאמר ר' יונה כי פירוש ויקח לקח לקום על משהו: NOW KORAH…TOOK. This is short for, now Korah took men.¹³The word men is not in the Hebrew text. Hence I.E.’s comment. Compare, an ass bread¹⁴Translated literally. (I Sam. 16:20).¹⁵An ass bread is short for an ass carrying bread. There are many such instances in Scripture.¹⁶Where a word is left out of the text. Rabbi Jonah says that the meaning of Now Korah took is now Korah took himself to rise against Moses.¹⁷Rabbi Jonah connects Now Korah…took (v. 1) to and they rose up (v. 2).