A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
ezr 9:1EZRA MOURNS FOR THE AFFINITY OF THE PEOPLE WITH STRANGERS. (Ezr 9:1-4)
Now when these things were done--The first days after Ezra's arrival in Jerusalem were occupied in executing the different trusts committed to him. The nature and design of the office with which the royal authority had invested him was publicly made known to his own people by the formal delivery of the contribution and the sacred vessels brought from Babylon to the priests to be deposited in the temple. Then his credentials were privately presented to the provincial governors; and by this prudent, orderly proceeding he put himself in the best position to avail himself of all the advantages guaranteed him by the king. On a superficial view everything contributed to gratify his patriotic feelings in the apparently flourishing state of the church and country. But a further acquaintance discovered the existence of great corruptions, which demanded immediate correction. One was particularly brought under his notice as being the source and origin of all others; namely, a serious abuse that was practised respecting the law of marriage.
the princes came to me, saying--The information they lodged with Ezra was to the effect that numbers of the people, in violation of the divine law (Deu 7:2-3), had contracted marriages with Gentile women, and that the guilt of the disorderly practice, far from being confined to the lower classes, was shared in by several of the priests and Levites, as well as of the leading men in the country. This great irregularity would inevitably bring many evils in its train; it would encourage and increase idolatry, as well as break down the barriers of distinction which, for important purposes, God had raised between the Israelites and all other people. Ezra foresaw these dangerous consequences, but was overwhelmed with a sense of the difficulty of correcting the evil, when matrimonial alliances had been formed, families had been reared, affections engaged, and important interests established.
ezr 9:3when I heard this thing, I rent my garment and my mantle, &c.--the outer and inner garment, which was a token not only of great grief, but of dread at the same time of the divine wrath;
plucked off the hair of my head and of my beard--which was a still more significant sign of overpowering grief.
ezr 9:4Then were assembled unto me every one that trembled at the words of the God of Israel, &c.--All the pious people who reverenced God's word and dreaded its threatenings and judgments joined with Ezra in bewailing the public sin, and devising the means of redressing it.
I sat astonied until the evening sacrifice--The intelligence of so gross a violation of God's law by those who had been carried into captivity on account of their sins, and who, though restored, were yet unreformed, produced such a stunning effect on the mind of Ezra that he remained for a while incapable either of speech or of action. The hour of the evening sacrifice was the usual time of the people assembling; and at that season, having again rent his hair and garments, he made public prayer and confession of sin.
ezr 9:5PRAYS TO GOD. (Ezr 9:5-15)
I fell upon my knees, and spread out my hands unto the Lord my God--The burden of his prayer, which was dictated by a deep sense of the emergency, was that he was overwhelmed at the flagrant enormity of this sin, and the bold impiety of continuing in it after having, as a people, so recently experienced the heavy marks of the divine displeasure. God had begun to show returning favor to Israel by the restoration of some. But this only aggravated their sin, that, so soon after their re-establishment in their native land, they openly violated the express and repeated precepts which commanded them to extirpate the Canaanites. Such conduct, he exclaimed, could issue only in drawing down some great punishment from offended Heaven and ensuring the destruction of the small remnant of us that is left, unless, by the help of divine grace, we repent and bring forth the fruits of repentance in an immediate and thorough reformation.