يَا أَيُّهَا الَّذِينَ آمَنُوا إِن جَاءكُمْ فَاسِقٌ بِنَبَأٍ فَتَبَيَّنُوا أَن تُصِيبُوا قَوْمًا بِجَهَالَةٍ فَتُصْبِحُوا عَلَى مَا فَعَلْتُمْ نَادِمِينَ
Hujuraat 49: 6. O you who believe! If a rebellious evil person comes to you with a news, verify it, lest you harm people in ignorance, and afterwards you become regretful to what you have done.
It was narrated that Hafs ibn ‘Aasim said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “It is enough lying for a man to speak of everything that he hears.” Narrated by Muslim in al-Muqaddimah, 6; Saheeh al-Jaami, 4482.
Umar (may Allaah be pleased with him) said: “Beware of fitnah, for a word at the time of fitnah could be as devastating as the sword.”
Al-Hasan al-Basri said: “The believer reserves judgement until the matter is proven.”