Sayyiduna Uqbah bin Amir (may Allah be pleased with him) narrates: A silk cloak was presented to the Prophet Muhammad (peace be upon him). The Prophet (peace be upon him) wore it and then performed prayer in it. After completing the prayer, he took it off with displeasure and said: "This is not suitable for the pious."
(Imam Ibn Hibban, may Allah have mercy on him, says:) By 'furooj hareer' is meant that garment whose warp is of silk; it is not entirely made of silk. If it were entirely made of silk, the Prophet (peace be upon him) would neither have worn it nor performed prayer in it. The same meaning is derived from the narration attributed to Sayyiduna Umar bin Khattab (may Allah be pleased with him): only two, three, or four finger-widths (of silk strip) are permitted.
Hadith Referenceصحیح ابن حبان / كتاب اللباس وآدابه / 5433
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح: ق.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم