“O you who believe! Be afraid of Allah, and be with those who are true (in words and deeds.)” (Qur’an, 9:119)
“Obedience (to Allah) and good words (were better for them). And when the matter (preparation for Jihad) is resolved on, then if they had been true to Allah, it would have been better for them.” (Qur’an, 47:21)
Prophet Muhammad (peace be upon him) said, “A true action leads to the path of virtue and good deeds, and virtue paves the way for a person to Paradise. A person continues to speak the truth till in the sight of Allah he is named Siddiq or Truthful. Lying leads to vice, and vice leads to indecent acts. A person continues to lie till in the sight of Allah he is named a liar.” (Bukhari and Muslim)
Prophet Muhammad (peace be upon him) said: “Leave alone that which puts thee in doubt, and adhere to that which is free from doubt, for truth is comforting and falsehood is disturbing.” (Tirmidhi)
The Prophet (peace be upon him) said about business transactions: “A sale agreement is revocable till the buyer and seller part company. If they tell the truth and disclose everything relevant to the transaction, it becomes full of blessings for both of them; but if they speak falsely and conceal what should be disclosed, the blessing of the transaction is withheld.” (Bukhari and Muslim).