Sahih Muslim: Chapter 40 : FORBIDDANCE OF PRIDE
Book 1, Number 0164:
It Is narrated on the authority of Abdullah b. Mas'ud that the Apostle of Allah (may peace be upon him), observed: He who has in his heart the weight of a mustard seed of pride164 shall not enter Paradise. A person (amongst his hearers) said: Verily a person loves that his dress should be fine, and his shoes should be fine. He (the Holy Prophet) remarked: Verily, Allah is Graceful and He loves Grace165. Pride is disdaining the truth166 (out of self-conceit) and contempt for the people167.
Book 1, Number 0165:
It is narrated on the authority of 'Abdullah b. Mas'ud that the Messenger of Allah (may peace be upon him) observed: None shall enter the Fire (of Hell) who has in his heart the weight of a mustard seed of Iman and none shall enter Paradise who has in his heart the weight of a mustard seed of pride.
Book 1, Number 0166:
It is narrated on the authority of 'Abdullah that the Apostle of Allah (may peace be upon him) observed: He who as in his heart the weight of a mustard seed of pride shall not enter Paradise.
(Slightly Edited English) Commentary by Maulana Abdul Hamid Siddiqui (translator of Sahih Muslim)
Note 164. Pride is the offspring of self-conceit, and this is the very negation of faith. Pride and faith can not thus go together. Iman inculcates in man the spirit of humility and submission to Truth. Pride is the expression of vanity which is one of the greatest hurdles in the path of truth. The self-conceited man accepts nothing unless it satisfies his vanity and, therefore, he can not be a true believer. He is a worshipper of his "own self".
Note 165. Islam does not teach asceticism and, therefore, does not blunt the aesthetic sense of man. It is with Beauty and Grace that the Lord has created this universe, and man, by his very nature, has a love for these two qualities. Islam makes no attempt to deprive man of his natural urges but canalises his aesthetic sense to fruitful channels. It exhorts its followers not to lead a life of renunciation but to use the bounties of the Lord according to His Command. There is no idea of the depravity of human nature in Islam, because man is not born with a stigma and his natural instincts are not the mainsprings of vices. They are primarily good in themselves provided they are satisfied in accordance with the Commands of God.
Note 166. The Holy Quran has mentioned at numerous places that it is vanity and self-conceit which stand in the way of man in accepting the Truth, e.g., it was out of pride that Iblis refused to obey the command of Allah:
002.034 And behold, We said to the angels: "Bow down to Adam" and they bowed down. Not so Iblis: he refused and was haughty: He was of those who reject Faith.
002.087 We gave Moses the Book and followed him up with a succession of apostles; We gave Jesus the son of Mary Clear (Signs) and strengthened him with the holy spirit. Is it that whenever there comes to you an apostle with what ye yourselves desire not, ye are puffed up with pride?- Some ye called impostors, and others ye slay!
007.040 To those who reject Our signs and treat them with arrogance, no opening will there be of the gates of heaven, nor will they enter the garden, until the camel can pass through the eye of the needle: Such is Our reward for those in sin.
Note 167. The vain and self-conceited persons not only belie the truth, but they even look down upon the people who have ties of human brotherhood with them. They consider themselves to be superior beings marked off from the rest of mankind. The Holy Quran says:
031.018 "And swell not thy cheek (for pride) at men, nor walk in insolence through the earth; for God loveth not any arrogant boaster.
031.019 "And be moderate in thy pace, and lower thy voice; for the harshest of sounds without doubt is the braying of the ass."