Masrouq bin al-Ajda' مسروق بن الأجدع · The Chapters on Rulings

“Whoever takes the wrongdoer's side in a dispute or supports wrongdoing, he will remain subject to the wrath of Allah until he gives it up.”

the Prophet(ﷺ) prayed the Morning prayer, and when he had finished, he stood up and said: “Bearing false witness is equivalent to associating others with Allah,” three times. Then he recited this Verse: “And shun lying speech (false statements), Hunafa' Lillah (i.e., worshiping none but Allah), not associating partners (in worship) to Him.”

the Messenger of Allah (ﷺ) allowed the People of the Book to testify against one another.