Shama-il Tirmidhi

Saa-ib bin Yazid (Radiallahu anhu) said: "My (maternal) aunt took to me to the Holy Prophet (Sallallahu alaihe wasallam) and said to him, this nephew of mine is ill. Rasulullah (Sallallahu alaihe wasallam) wiped his holy hand over my head and made for barakah for me. (According to some Ulama, Rasulullah (Sallallahu alaihe wasallam) wiped his hand over his head, meant that he Sayyidina Saa-ib bin Yazid (Radiallahu anhu) had a pain in the head. The opinion of this weak and humble servant is that it is better if this is taken to mean that the Holy Prophet (Sallallahu alaihe wasallam) wiped his hands in kindness on the head of Sayyidina Saa-ib bin Yazid (Radiallahu anhu). Sayyidina Saa-ib bin Yazid (Radiallahu anhu) was born in the second year Hijri, and at the time of the Holy Prophet (Sallallahu alaihe wasallam)'s death, his age was not more than 8 or 9 years. That is why the Holy Prophet (Sallallahu alaihe wasallam) wiped his Holy hand in kindness, as is the customs of the great personalities. The Holy Prophet (Sallallahu alaihe wasallam) also gave him the water of wudu to drink as a cure, as will be stated further, or he may have prescribed another remedy, especially when we learn also in a narration in Bukhari thay he Sayyidina Saa-ib bin Yazid (Radiallahu anhu)was suffering from pain in his leg). When the Holy Prophet (Sallallahu alaihe wasallam) performed Wudu, I drank the water of that wudu. (The Holy Prophet (Sallallahu alaihe wasallam) may have performed wudu for some reason, but here it is clear that the Holy Prophet (Sallallahu alaihe wasallam) performed wudu so that the water could be used as a remedy and medicine). I saw the seal of Prophethood, which was like the knot on a mosquito net or bedstead." (Which is the size of a pigeon's egg in roundness). The Ulama differ in the translation of this word. Some have translated it in another manner. Imam Nawawi, the famous commentator of Sahih Muslim, preferred the translation I have chosen).

Commentary.
If in this Hadith the left over water of wudu is meant, then there is no difficulty or difference of opinion. If that water is meant which falls after washing the limbs etc., which in Arabic is known as 'Mae Musta'amal', then too there is no complication or difficulty, because even the excrements of Sayyidina Rasulullah (Sallallahu alaihe wasallam) is paak. So how can there be a complaint regarding the 'Mae Musta'amal'(Used water).