Al-Harith narrates from Sayyiduna Ali (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "O Ali! I love for you what I love for myself, and I dislike for you what I dislike for myself. Do not recite the Qur'an while bowing, nor while prostrating; do not pray with your hair tied up in a knot, for it is the Shaytan's seat; do not squat (iq'a') between the two prostrations; do not play with the pebbles; do not spread out your forearms (on the ground); do not prompt the imam; do not wear a gold ring; do not wear qassi garments; and do not ride on silk saddle-cushions, that is, do not sit on them."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5790