Deuteronomy 19:18

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

Deuteronomy 13:14

then shalt thou inquire, and make search, and ask diligently; and, behold, if it be truth, and the thing certain, that such abomination is wrought in the midst of thee,

Deuteronomy 17:4

and it be told thee, and thou hast heard of it, then shalt thou inquire diligently; and, behold, if it be true, and the thing certain, that such abomination is wrought in Israel,

2 Chronicles 19:6-7

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

Job 19:16

I call unto my servant, and he giveth me no answer, Though I entreat 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 shalt thou inquire, and make search, and ask diligently; and, behold, if it be truth, and the thing certain, that such abomination is wrought in the midst of thee,
Deuteronomy 17:4
and it be told thee, and thou hast heard of it, then shalt thou inquire diligently; and, behold, if it be true, and the thing certain, that such abomination is wrought in Israel,
2 Chronicles 19:6
and said to the judges, Consider what ye do: for ye judge not for man, but for Jehovah; and he is with you in the judgment.
Job 19:16
I call unto my servant, and he giveth me no answer, Though I entreat him with my mouth.

General references

Deuteronomy 5:20
Neither shalt thou bear false witness against thy neighbor.
Deuteronomy 25:1
If there be a controversy between men, and they come unto judgment, and the judges judge them; then they shall justify the righteous, and condemn the wicked;
John 7:51
Doth our law judge a man, except it first hear from himself and know what he doeth?

American Standard Version Public Domain