Taking back one's sheep within one's allocated Zakah-tenth

Q : I am the authorized Zakah (obligatory charity) officer of the tribe of Al Zabanah Al Hayyan. When taking the Zakah-tenth from the third center of Zakah collectors in Tihamah Qahtan, they gave me sheep including my own sheep that I delivered to them as the due Zakah on my sheep. Is it permissible for me to take my sheep that I paid to them as Zakah in the Zakah-tenth given to me from the entire amount of Zakah? A : When they give your allocated Zakah-tenth and your sheep that you delivered as Zakah included therein, it is impermissible for you to take it, because the Prophet (may Allah's Peace and Blessings be upon him) forbade `Umar (may Allah be pleased with him) from returning a horse that was given as Sadaqah (voluntary charity) and said: Do not buy it from him even if he sells it to you for a dirham. Therefore, if this is the case with what a person may return through purchase, it is more fitting to be applied to what is taken for free [if buying the Sadaqah that a person gave is forbidden, then taking it back for free is also forbidden]. (Part No. 8; Page No. 19

A : When they give your allocated Zakah-tenth and your sheep that you delivered as Zakah included therein, it is impermissible for you to take it, because the Prophet (may Allah's Peace and Blessings be upon him) forbade `Umar (may Allah be pleased with him) from returning a horse that was given as Sadaqah (voluntary charity) and said: Do not buy it from him even if he sells it to you for a dirham. Therefore, if this is the case with what a person may return through purchase, it is more fitting to be applied to what is taken for free [if buying the Sadaqah that a person gave is forbidden, then taking it back for free is also forbidden]. (Part No. 8; Page No. 19) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.