Ezra was praying and confessing, weeping and throwing himself down before the house of God

Ezra 10:1-44
While Ezra was praying and confessing, weeping and throwing himself down before the house of God, a large crowd of Israelites—men, women and children—gathered around him. They too wept bitterly.
Now let us make a covenant before our God to send away all these women and their children, in accordance with the counsel of my lord and of those who fear the commands of our God. Let it be done according to the Law. Rise up; this matter is in your hands. We will support you, so take courage and do it.
On the first day of the tenth month they sat down to investigate the cases,  and by the first day of the first month they finished dealing with all the men who had married foreign women.
His close identification with the offenders and the deep grief of his prayer pricks the nation's conscience. They call on him so act. So, by their own choice, the whole assembly gathers to hear his judgment. We see them shivering in the December rains and can almost hear the interchange that follows.
The blame for all the unhappiness of broken marriages rests not on Ezra, but on those listed in 10:18-44 - the men who contracted those marriages in defiance of God's law. Some of them had even broken former marriages to Jewish wives to do so. 
The Hebrew Bible continues straight on from Ezra 10:44, without a break to the opening words of Nehemiah; the conclusion of the story. Ezra will reappear in a more positive role, as the people assemble again in Nehemiah Chapter 8 to hear God's law.
Why?
Ezra was praying and confessing weeping and throwing himself down before the house of God, people saw and heard what he prayed. So they gathered around him, they have the same mind as Ezra.
After prayer before the Lord, people supported Ezra and encouraged him, for Ezra have the authority to proclaim this and asked people come to Jerusalem.
Knowing the way of the Lord and making the procedure to execute the word of the Lord.
Prayer, let people know and do the action to exclude the evil things.
How?
Before action let pray before the Lord, asked the support of the Lord.