דַּבֵּ֞ר אֶל־כָּל־עֲדַ֧ת בְּנֵי־יִשְׂרָאֵ֛ל וְאָמַרְתָּ֥ אֲלֵהֶ֖ם קְדֹשִׁ֣ים תִּהְי֑וּ כִּ֣י קָד֔וֹשׁ אֲנִ֖י יְהוָ֥ה אֱלֹהֵיכֶֽם׃
"Parle à toute la communauté des enfants d’Israël et dis-leur: Soyez saints! Car je suis saint, moi l’Éternel, votre Dieu.
Siftei Chakhamim
Say (אמור), and you shall say. The verse should only have written, “Speak, to the kohanim.” Therefore [the apparent redundancy teaches us that], “speak” is to warn [the adult kohanim] themselves, “and you shall say” is to warn the adults regarding the minors. You might ask why Rashi does not also say this answer [regarding the verse] “Speak (דבר) (to the entire congregation [of] Bnei Yisroel) and say (אמרת) (to them)” in parshas Kedoshim (Vayikra 19:2). The answer is that דבור is a general [command to speak] and does not explain what the statement will be, while אמרת implies something specific, i.e., say this [particular] thing. Here however, where אמור is [already] specific, Rashi is asking why one needs [a command to say] two specific [statements].
Ibn Ezra
God told Moshe The preceding commandments are binding upon Israel, to the exclusion of the resident alien (which is why they were introduced by “Tell the entire community of the [Children of] Israel” [19:2]). Scripture is now about to describe punishments for sexual crimes, which are applicable to anyone who lives in the land of Israel — native and alien alike. who gives any of his children to Molekh This is the gravest of all sexual crimes: to sleep with an idolater, and to father her children. Thus it is mentioned first.
Ramban
SPEAK UNTO THE CHILDREN OF ISRAEL. Since this chapter deals with [the laws of] prohibited sexual intercourse which apply equally to all Israel, therefore He said only, Speak unto the children of Israel, and did not specify the priests but included them together. Therefore He said at first, I am the Eternal your G-d, just as He did in the Ten Commandments [which He began with the words, I am the Eternal thy G-d].214Exodus 20:2. And the meaning of the verse, Speak unto the children of Israel, and say unto them: I am the Eternal your G-d, is as if He said, “Say unto them in My Name, ‘I am the Eternal your G-d.’” Similarly, Speak unto all the congregation of the children of Israel, and say unto them: Ye shall be holy, for I the Eternal your G-d am holy,215Further, 19:2. [means: “say unto them in My Name, ‘Ye shall be holy'”].
It is possible that the reason [why the verse does not say: “this is what G-d commanded,” is not because it means: “say unto them in My Name” as explained above, but] is rather as follows: When Moses came out from before the Eternal without the veil216Exodus 34:33-35. [on his face], and he came out, and spoke unto the children of Israel that which he was commanded,217Ibid., Verse 34. he did not need to say to them: “Thus said the Eternal,” for it was known to them that it was His spirit that spoke through him [Moses] and His word was upon his tongue,218See II Samuel 23:2. Hence it is no longer necessary to explain the meaning of the verse to be [as we said above]: “Speak unto the children of Israel, and say unto them in My Name, I am the Eternal your G-d,” since it was known to them that Moses did not speak in his own name. and that he did not speak in his own name. Similarly, in many places in the Book of Deuteronomy it is stated in the same way, such as: And it shall come to pass, if ye shall hearken diligently unto My commandments, which I command you this day … that I will give the rain of your Land … And I will give grass in thy fields,219Deuteronomy 11:13-15. and [it is known that] Moses is not the one who giveth rain upon the earth, and sendeth waters upon the fields,220Job 5:10. and makes the grass grow in the fields, but it is G-d, blessed be He [that does these things]. Similarly it is said, But the Eternal hath not given you a heart to know … And I have led you forty years in the desert … Ye have not eaten bread, neither have ye drunk wine or strong drink; that ye might know that I am the Eternal your G-d.221Deuteronomy 29:3-5. The opening verse [But the Eternal …] clearly indicates that the expression in the following verse, And I have led you etc. is also a reference to the Eternal, and not to Moses. The meaning of the expression to love the Eternal your G-d222Ibid., 11:13. [which is stated in the third person, when that same verse begins in the first person, And it shall come to pass, if ye shall hearken diligently unto My commandments], has already been explained.223Exodus 24:1 (towards end — Vol. II, p. 422-3).
It is possible that the reason [why the verse does not say: “this is what G-d commanded,” is not because it means: “say unto them in My Name” as explained above, but] is rather as follows: When Moses came out from before the Eternal without the veil216Exodus 34:33-35. [on his face], and he came out, and spoke unto the children of Israel that which he was commanded,217Ibid., Verse 34. he did not need to say to them: “Thus said the Eternal,” for it was known to them that it was His spirit that spoke through him [Moses] and His word was upon his tongue,218See II Samuel 23:2. Hence it is no longer necessary to explain the meaning of the verse to be [as we said above]: “Speak unto the children of Israel, and say unto them in My Name, I am the Eternal your G-d,” since it was known to them that Moses did not speak in his own name. and that he did not speak in his own name. Similarly, in many places in the Book of Deuteronomy it is stated in the same way, such as: And it shall come to pass, if ye shall hearken diligently unto My commandments, which I command you this day … that I will give the rain of your Land … And I will give grass in thy fields,219Deuteronomy 11:13-15. and [it is known that] Moses is not the one who giveth rain upon the earth, and sendeth waters upon the fields,220Job 5:10. and makes the grass grow in the fields, but it is G-d, blessed be He [that does these things]. Similarly it is said, But the Eternal hath not given you a heart to know … And I have led you forty years in the desert … Ye have not eaten bread, neither have ye drunk wine or strong drink; that ye might know that I am the Eternal your G-d.221Deuteronomy 29:3-5. The opening verse [But the Eternal …] clearly indicates that the expression in the following verse, And I have led you etc. is also a reference to the Eternal, and not to Moses. The meaning of the expression to love the Eternal your G-d222Ibid., 11:13. [which is stated in the third person, when that same verse begins in the first person, And it shall come to pass, if ye shall hearken diligently unto My commandments], has already been explained.223Exodus 24:1 (towards end — Vol. II, p. 422-3).