Deuteronomy 19:18

and the judges shall make diligent inquisition: and, behold, if the witness is a false witness, and has testified falsely against his brother;

Deuteronomy 13:14

then you shall inquire, and make search, and ask diligently; and, behold, if it be truth, and the thing certain, that such abomination is done in the midst of you,

Deuteronomy 17:4

and it be told you, and you have heard of it, then you shall inquire diligently; and behold, if it be true, and the thing certain, that such abomination is done in Israel,

2 Chronicles 19:6-7

and said to the judges, "Consider what you do: for you do not judge for man, but for the LORD; and he is with you in the judgment.

Job 19:16

I call to my servant, and he gives me no answer. I beg him with my mouth.

Treasury of Scripture Knowledge

Summary

And the judges shall make diligent inquisition: and, behold, if the witness be a false witness, and hath testified falsely against his brother;

Bible References

Diligent

Deuteronomy 13:14
then you shall inquire, and make search, and ask diligently; and, behold, if it be truth, and the thing certain, that such abomination is done in the midst of you,
Deuteronomy 17:4
and it be told you, and you have heard of it, then you shall inquire diligently; and behold, if it be true, and the thing certain, that such abomination is done in Israel,
2 Chronicles 19:6
and said to the judges, "Consider what you do: for you do not judge for man, but for the LORD; and he is with you in the judgment.
Job 19:16
I call to my servant, and he gives me no answer. I beg him with my mouth.

General references

Deuteronomy 5:20
"And you shall not give false testimony against your neighbor.
Deuteronomy 25:1
If there is a controversy between men, and they come to judgment, and the judges judge them; then they shall justify the righteous, and condemn the wicked;
John 7:51
"Does our Law judge a man, unless it first hears from him personally and knows what he does?"