Muhammad Ibn Abi U’mair had the opportunity of serving Imam Kadhim, Imam Ridha and Imam Jawad (a.s.) and both, the Sunnites and the Shiites, have attested to his trustworthiness and uprightness.
He was a cloth-merchant by profession and financially very well off. He wrote ninety-four books on traditions and jurisprudence. Due to his stateliness, and his knowledge of the names of the Shiites, he used to be greatly troubled during the period of Haroon Al-Rashid and Mamun; he would be abused, imprisoned and his property would be seized. He was asked to become a judge, but he declined the offer; since he was familiar with the Shiites of Iraq, he was asked to reveal their names, but he refused to comply so they flung him into prison and, on numerous occasions, he was whipped so severely that he was barely left alive. Once, upon the orders of Haroon Al-Rashid, Sindi Ibn Shaahak subjected him to a hundred and twenty lashes and he had to purchase his freedom by paying one thousand dirhams. Financially, he suffered a loss of a hundred thousand dirhams and his captivity extended for a period of four years.
His sister (Sa’eedah or Minnah) gathered all his books and concealed them, but it so happened that one day it rained and all his books were ruined. Later, the traditions that he used to narrate were either from the sharp memory, which he possessed, or from copies, which others had transcribed from his original books before their destruction. ( Muntahal Aa’maal, vol. 2, pg. 358.)