Romans 11:10

Eyes be darkened. For the darkening of eyes as a figure of the spiritual blindness to come upon Israel see on Isa. 6:9, 10. Thus the Jews, though they possessed clear revelations of God’s will, remained ignorant of the real meaning and purpose of these revelations, whereas the less favored but teachable Gentiles were able to understand.

Bow down. Gr. sugkampto, literally, “to bend together,” as of captives whose backs have been bent under burdens. In the OT this psalm reads, “make their loins continually to shake.” Paul’s statement agrees with the LXX. The picture suggested is that of servile fear and dejection. This verse well describes the condition of the unbelieving Jews. So long had they devoted their attention to external forms and trivial details of ritual and ceremony that they were destitute of all spiritual discernment and of the capacity to appreciate essential moral and spiritual truths (see Matt. 23:23-25; Mark 7:2-9). In their continued attempts to establish their own righteousness in this manner, they had ever increased the burden of legal requirements (see Matt. 23:4).

By using these quotations from the OT Paul has shown that the serious picture he has been compelled to draw of the condition of his fellow Jews is clearly supported by the Scriptures which they believe. Moreover, their sinful condition is no new development, but has distinguished them since the days of Moses and the prophets.