Аль-Ахкаф 46:11

Initially, of the people who became the companions of the Prophet of God, many were old and belonged to the slave class, for example, Bilal, ‘Ammar, Shu‘ayb, Khubbab, etc. At the same time, among those who had faith in him, there were also people who belonged to respectable families, such as Abu Bakr ibn Abi Qahafa, ‘Uthaman ibn ‘Affan, ‘Ali ibn Abi Talib, etc. But the Prophet’s opponents used to mention only the former and not the latter. The reason is that when anyone becomes biased against a particular individual, his attitude becomes one-sided. He ignores the latter’s virtues and mentions only those aspects of him which give him the opportunity to degrade him. Similarly, the call of the Prophet Muhammad was undoubtedly the same as that of all the previous prophets: he had come with an eternal truth. But his opponents, instead of calling it ‘a very old truth’, called it ‘a very old falsehood.’ This kind of injustice prevailed in former times and, even today, it is quite common.