Ibn Mas'ud (May Allah be pleased with him) said:
The Prophet (ﷺ) said, "Shall I tell you what 'Al-'Adhu' (falsehood and slandering) is? It is calumny which is committed among the people."[Muslim]. (IT)
App reference (IT): Book 18, Hadith 28 (IT)
Arabic/English book reference (IT): Book 18, Hadith 1538 (IT)