Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
Two liturgical enactments having a clear and close reference to the whole of the preceding legislation, form a most appropriate and significant conclusion to it, namely,
(1) the formal acknowledgment in deed and symbol of God's faithfulness, by presentment of a basket filled with firstfruits, and in word by recitation of the solemn formula prescribed in Deu 26:3, Deu 26:5-10; and
(2) the solemn declaration and profession on the part of each Israelite on the occasion of the third tithe Deu 26:12.
On the subject of firstfruits see the notes at Lev 23:9 ff. The firstfruits here in question are to be distinguished alike from those offered in acknowledgment of the blessings of harvest (compare Exo 22:29) at the Feasts of Passover and Pentecost, and also from the offerings prescribed in Num 18:8 ff. The latter consisted of preparations from the produce of the earth, such as oil, flour, wine, etc.; while those here meant are the raw produce: the former were national and public offerings, those of this chapter were private and personal. The whole of the firstfruits belonged to the officiating priest.
A Syrian ready to perish was my father - The reference is shown by the context to be to Jacob, as the ancestor in whom particularly the family of Abraham began to develop into a nation (compare Isa 43:22, Isa 43:28, etc.). Jacob is called a Syrian (literally, Aramaean), not only because of his own long residence in Syria with Laban Gen. 29-31, as our Lord was called a Nazarene because of his residence at Nazareth Mat 2:23, but because he there married and had his children (compare Hos 12:12); and might be said accordingly to belong to that more than to any other land.
See the marginal reference to Numbers and note. A strict fulfillment of the onerous and complicated tithe obligations was a leading part of the righteousness of the Pharisees: compare Mat 23:23.
I have not eaten thereof in my mourning - When the Israelite would be unclean (compare the marginal references).
Nor given ought thereof for the dead - The reference is not so much to the superstitious custom of placing food on or in tombs as to the funeral expenses, and more especially the usual feast for the mourners (compare Jer 16:7; Eze 24:17; Hos 9:4; Tobit 4:17). The dedicated things were to be employed in glad and holy feasting, not therefore for funeral banquets; for death and all associated with it was regarded as unclean.
A brief and earnest exhortation by way of conclusion to the second and longest discourse of the book.
Thou hast avouched - literally, "made to say:" so also in the next verse. The sense is: "Thou hast given occasion to the Lord to say that He is thy God," i. e. by promising that He shall be so. Compare Exo 24:7; Jos 24:14-25,