What Hale says regarding Proctor's deposition is:

HALE: Excellency, a moment. I think this goes to the heart of the matter... I cannot say he is an honest man; I know him little. But in all justice, sir, a claim so weighty cannot be argued by a farmer. In God's name, sir, stop here; send him home and let him come again with a lawyer—Excellency, I have signed seventy-two death warrants; I am a minister of the Lord, and I dare not take a life without there be proof so immaculate no slightest qualm of conscience may doubt it. 

Hale is one of the most interesting characters in The Crucible because of his significant character arc. In this moment, Hale has transitioned from his starting point in the play, where he was sure of witchcraft and actively guiding potential witches to plead guilty. Now, however, Hale is beginning to believe that the paranoia within the town is dangerous. As a minister, Hale does not want to put innocent people to death. The hysteria has grown too large, though, and many innocent lives are being risked, as seen in the cases of Proctor and Elizabeth and many of the townspeople. Consequently, Hale thinks it would be wise for Proctor to consult a lawyer, as this would guide Proctor's response in a way that could potentially save his life. Danforth finds this suspicious, though, and sees Hale's interruption as doubting Danforth's justice. Hale's advice is not followed and Hale eventually leaves the court.

Proctor again presents Mary Warren’s deposition, which states that “she never saw Satan; nor any spirit, vague or clear, that Satan may have sent to hurt her. And she declares her friends are lying now.” At this point, realizing the seriousness of the statement, Hale suggests that Proctor return with a lawyer to present this claim. Hale has begun to see how uncertain the evidence is against those who have been condemned to die.

In Act Three, just as Proctor is about to hand his deposition to Deputy Governor Danforth, Mr. Hale implores Danforth, "in all justice, sir, a claim so weighty cannot be argued by a farmer.  In God's name, sir, stop here; send him home and let him come again with a lawyer--."  He believes that Proctor brings legitimate evidence to the court, and he is concerned that a farmer does not have the experience and knowledge to address the court on such an important matter.  Hale is much more willing to believe that this deposition could contain some truth than Danforth seems to be.  Danforth says that it is the "contention of the state [...] that the voice of Heaven is speaking through the children."  However, Hale is more concerned that they not execute any innocents when there is evidence calling their guilt into question.