It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that some people brought a companion of theirs to the Prophet (peace and blessings be upon him) and said: "O Prophet of Allah, modesty has spoiled this companion of ours." The Prophet (peace and blessings be upon him) said: "Modesty is part of the laws of Islam, and foul speech is part of a man's baseness."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10460