Allah Almighty says: {and shun the words of falsehood} [Surat al-Hajj: 30] And He says: {And do not follow that of which you have no knowledge} [Surat al-Isrā’: 36] And He says: {Not a single word he utters but there is with him a vigilant watcher, ready [to record it].} [Surat Qāf: 18] And He says: {Indeed, your Lord is ever vigilant.} [Surat al-Fajr: 14] And He says: {And those who do not witness falsehood} [Surat al-Furqān: 72]
False testimony: to give testimony contrary to what happened in reality.
2) Giving a false testimony is prohibited because it is one of the gravest major sins; it is included in the {words of falsehood} mentioned in the verse.
3) Refraining from giving false testimony is one of the characteristics of the pious slaves of the Most Merciful.
1550/1- Abu Bakrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah’s peace and blessings be upon him) said: “Shall I inform you of the gravest major sins?” We said: “Yes, please do, O Messenger of Allah?” He said: “Associating partners with Allah, and undutifulness to parents.” He was reclining, so he sat up and said: “Beware of making a false statement!” He kept repeating it until we wished he would stop. [Narrated by Al-Bukhāri and Muslim]
1) The Hadīth warns against making false statements; the Messenger of Allah (may Allah’s peace and blessings be upon him) coupled it with committing Shirk and undutifulness to the parents. Also, Allah Almighty says: {So shun the impurity of idolatry and shun the words of falsehood.}
2) One of the tips for good teaching is for the teacher to repeat significant matters in order to be understood and for the listener to pay attention.