Deuteronomy 19:18

and the judges have searched diligently, and lo, the witness is a false witness, a falsehood he hath testified against his brother:

Deuteronomy 13:14

and thou hast enquired, and searched, and asked diligently, and lo, truth; the thing is established; this abomination hath been done in thy midst:

Deuteronomy 17:4

and it hath been declared to thee, and thou hast heard, and hast searched diligently, and lo, truth; the thing is established; this abomination hath been done in Israel --

2 Chronicles 19:6-7

and saith unto the judges, 'See what ye are doing -- for not for man do ye judge, but for Jehovah, who is with you in the matter of judgment;

Job 19:16

To my servant I have called, And he doth not answer, With my mouth I make supplication to him.

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
and thou hast enquired, and searched, and asked diligently, and lo, truth; the thing is established; this abomination hath been done in thy midst:
Deuteronomy 17:4
and it hath been declared to thee, and thou hast heard, and hast searched diligently, and lo, truth; the thing is established; this abomination hath been done in Israel --
2 Chronicles 19:6
and saith unto the judges, 'See what ye are doing -- for not for man do ye judge, but for Jehovah, who is with you in the matter of judgment;
Job 19:16
To my servant I have called, And he doth not answer, With my mouth I make supplication to him.

General references

Deuteronomy 5:20
Thou dost not answer against thy neighbour -- a false testimony.
Deuteronomy 25:1
'When there is a strife between men, and they have come nigh unto the judgment, and they have judged, and declared righteous the righteous, and declared wrong the wrong-doer,
John 7:51
'Doth our law judge the man, if it may not hear from him first, and know what he doth?'