Zaid bin Aslam narrates that he saw Sayyiduna Abdullah bin Umar (may Allah be pleased with them) performing prayer with his button open. I asked him about this, and he replied: I saw the Prophet Muhammad (peace and blessings be upon him) performing prayer in this manner.

Abu Uthman narrates: The letter of Sayyiduna Umar (may Allah be pleased with him) reached us while we were in Azerbaijan with Utbah bin Farqad. (It was written in it:) "To proceed! Keep your buttons fastened, keep your shoes on, use light-weight arrows, and cut your trousers (a little above the ankles). It is obligatory upon you to wear the clothing of your ancestor, Sayyiduna Ismail (peace be upon him), and avoid (expensive and unnecessary) adornments and the customs of the non-Arabs. And it is obligatory upon you to stay in the sun, for this is the bathhouse of the Arabs. Wear rough and old clothes and ride on the bare back of the horse, for the Prophet (peace and blessings be upon him) forbade us from wearing silk, except for this much—meaning two fingers' width, the middle finger and the index finger."

The narrator says: To our knowledge, what is meant by this is a sign (i.e., using silk as a strip).