Hadith: Will you not listen? Will you not listen? Simplicity is part of faith, simplicity is part of faith

عن أبي أمامة إياس بن ثعلبة الأنصاري الحارثي رضي الله عنه قال: ذكر أصحاب رسول الله صلى الله عليه وسلم يوماً عنده الدنيا، فقال رسول الله صلى الله عليه وسلم: «ألا تسمعون؟ ألا تسمعون؟ إن البَذَاذَةَ من الإيمان، إن البَذَاذَةَ من الإيمان» قال الراوي: يعني التَّقحُّل.
[حسن لغيره] - [رواه أبو داود وابن ماجه وأحمد]

Abu Umāmah Iyās ibn Tha‘labah al-Ansāri al-Hārithi (may Allah be pleased with him) reported: The Companions of the Messenger of Allah (may Allah's peace and blessings be upon him) once mentioned the (luxuries) of the worldly life in his presence. So the Messenger of Allah (may Allah's peace and blessings be upon him) said: "Will you not listen? Will you not listen? Simplicity is part of faith, simplicity is part of faith."
[Hasan/Sound by virtue of corroborating evidence] - [Narrated by Ibn Majah - Narrated by Abu Daoud - Narrated by Ahmad]

Explanation

Some of the Prophet's Companions talked about the luxuries of the worldly life. So he said to them: "Will you not listen", in order to urge them to listen to what he was going to say, and repeated this to emphasize its importance. Then he told them that observing modesty in one's clothes and adornment is a manner of the people of faith, and that faith is what motivates a person to be modest.