Some claim that translating the word bar" (in Psalm 2:12) as "son" rather than as "purity" is a distortion of the Hebrew text in order to make the verse apply to Jesus. It is also claimed that this is not a Jewish interpretation of the verse. And finally, it is said that the word "bar" means "son" only in Aramaic, whereas this psalm is in Hebrew.
Yet some important Jewish sources translate "bar" as "son." The translation can be supported by linguistic arguments. Therefore there is no basis for claiming that this rendering is a "Christian mistranslation." Some of these sources are as follows:
The interpretation of Ibn Ezra (12th c.):
Ibn Ezra rejects the simple and acceptable meaning of 'bar' as pure and inclines to translate it as son, referring it to the "anointed one" in v. 2 and making it the apposite of "Thou art my son" in v. 7. Bar would then allude to Israel.
J. Sarachek, The Doctrine of the Messiah in Medieval Jewish Literature (New York: Hermon Press, 1968), p. 121.
The interpretation of David Kimchi (13th c.), observing the validity of "son" as well as "pure":
Qimchi observes that bar may either be the same as the common Hebrew ben, as in Prov. xxxi.2, or may mean "pure," as in the phrase "pure of heart." "If," he says, "we adopt the reading son, then the sense will be, 'kiss the son whom God hath called a son,' saying, 'Thou art my son;' and the verb must be explained by the custom of slaves kissing the hand of their masters. But if we adopt the reading pure, it means, 'What have I to do with you? for I am pure of heart, and there is no iniquity in me that you should come and fight against me; but it is your part to kiss me and to confess that I am king by the ordinance of God.'
cited in J. J. Stewart Perowne, The Book of Psalms: A New Translation with Introductions and Notes Explanatory and Critical (Grand Rapids: Zondervan, 1975), pp. 119-20.
The Isaac Leeser translation of the Hebrew Bible (19th c.):
Do homage to the son.
Isaac Leeser, Twenty-Four Books of the Holy Scriptures Carefully Translated After the Best Jewish Authorities (New York: Hebrew Publishing Company). Leeser's translation was the standard American Jewish translation from 1845 until the Jewish Publication Society translation of 1917.
Willem A. VanGemeren, Professor of Old Testament and Chairman, Dept. of O.T. Studies, Reformed Theological Seminary:
In favor of the traditional translation are the context of the psalm (submission to the Lord and to the anointed), the proposal by Delitzsch that the sequence bar pen ("Son, lest") avoids the dissonance of ben pen (KD, 1:98), and the suggestion by Craigie that the usage of the Aramaism may be intentionally directed to the foreign nations (Psalms 1-50, p. 64).
In The Expositor's Bible Commentary, ed. Frank E. Gaebelein, vol. 5 (Grand Rapids: Zondervan, 1991), p. 72.