Shama-il Tirmidhi Chapter 008, Hadith Number 004 (056).

Asmaa bint Yazeed Radhiyallahu 'Anha says: "The sleeve of Rasulullah Sallallahu 'Alayhi Wasallam's qamis reached to the wrists".

Commentary.
This narration apparently contradicts the one where it has been stated that the sleeves of the qamis of Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam were a bit longer than the wrist. The 'ulama have summed up the difference in several ways. Firstly, that at different times it had different lengths. Secondly, that when the sleeves were creased they were above the wrists, and when they were smooth and straight they were over the wrists. Some are of the opinion that both are taken on estimation. In this case there is no difficulty. Maulana Khalil Ahmad Saahib has written in the 'Badhlul Majhud' that where it is mentioned till the wrists, it is taken to be the best and desirable. Where the sleeves are stated to be longer, it is considered permissible. 'Allaamah Jazari states that it is sunnah that the length of the qamis (kurtah) sleeves reach till the wrists, and that of a jubbah be a bit longer, but in no case should it be longer than the fingers.