the Messenger of Allah (ﷺ) allowed the People of the Book to testify against one another.
Sunan Ibn Majah Book 13, Hadith 67
← Previous Hadith 'The one who bears false witness will not move away (on the Day of Resurrection) until Allah condemns him to Hell.' ”

Sunan Ibn Majah Book 13, Hadith 66 Next Hadith → “Bear witness that I have given Nu'man such and such from my wealth.” He said: “Have you given all your children something like that which you have given to Nu'man?” He said: “No.” He said: “Then let someone other than me bear witness to that.” And he said: “Would you not like all your children to honor you equally?” He said: “Of course.” He said: “Then do not do this.”

Sunan Ibn Majah Book 14, Hadith 1