Amir b. Sa'd reported on the authority of his father that Allah's Messenger (ﷺ) said:The greatest sinner amongst the Muslims is one who asked about a thing (from Allah's Apostle) which had not been forbidden for the Muslims and it was forbidden for them because of his persistently asking about it

This hadith has been transmitted on the authority of 'Amir b. Sa'd and the words are. Allah's Messenger (ﷺ) said:The greatest sinner of the Muslims amongst Muslims is one who asked about a certain thing which had not been prohibited and it was prohibited because of his asking about it

This hadith has been narrated on the authority of Zuhri with the same chain of transmitters and with this addition:" A person asked about a thing from Allah's Apostle (ﷺ) and he indulged in hair-splitting