ציטירנדיקער פּירוש אויף שמות 25:4

and with purple אַרְגְּוָן. This is synonymous with אַרְגָּמָן.

and crimson כַּרְמִיל. This is תוֹלַעַת שָׁנִי. The proof is that תוֹלַעַת שָׁנִי is not mentioned here.

שנים Scarlet (comp. Exod. 25:4). The idea contained in this verse is the reverse of that conveyed by the words of Jeremiah, Though thou wash thee with nitre, and take thee much soap, yet thine iniquity is marked before me (Jerem. 2:22); namely, the iniquity will depart, and you will again be free from all sin. The same is expressed by the words Wash you, etc. (ver. 16).

Come now, let us debate together, I and you, and we will know who offended whom, and if you offended Me, I still give you hope to repent.

If your sins prove to be like crimson Stained before Me like crimson red, I will make them as white as snow.

says the Lord [The verb is in the future form to denote that] He always says this to you, like: (Num. 9:20) “By the word of the Lord they would camp (יַחֲנוּ),” also a future form. Another explanation is: Come now, let us debate. What is written above this? “Cease to do evil; learn to do good.” And after you return to Me, come now, and let us debate together, to notify Me, “We have done what is incumbent upon us; You do what is incumbent upon You;” and I say, “If your sins prove to be like crimson, they will become white as snow...”

as crimson dye Heb. תּוֹלָע, lit. a worm. Dye with which they dye fabrics red. They are kernels, each one of which has a worm inside it. Hence the name תּוֹלָע.