Sahih Muslim: Book 1, Chapter 40, No. 164; Page 53.
(Hadith #164) It is narrated on the authority of ‘Abdullah b. Mas’ud that the Apostle of Allah (صَلَّى اللهُ عَلَيْهِ وَ سَلَّمُُ) observed: He who has in his heart the weight of a grain of mustard seed of pride  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 Greatest and He loves Grace. Pride is disdaining the truth  (out of self-conceitedness) and contempt for the people. 
Note 164: Pride is the offspring of self-conceitedness, and this is the very negation of faith. Pride and faith cannot 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 which does not satisfy his vanity and, therefore, he cannot 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 ascetic sense in 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 canalizes his ascetic 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 Qur’an has mentioned at numerous places that it is vanity and self-deceit which stand in the way of man accepting the Truth, e.g. it was out of pride that Iblis refused to obey the command of Allah (ii. 34).
“Is it then that whenever there came to you a messenger with what your souls desired not, you were arrogant? And some of you belied and some of you slew,” (ii. 87).
“Those who belie Our Signs and turn away from them in arrogance, the doors of Heaven will not be opened for them, nor will they enter the Garden, until the camel pass through the eye Of the needle. And thus do We reward the guilty,” (vii. 40).
Note 167: The vain and self-deceit 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 Qur’an says:
“And turn not thy face away from people in contempt, nor go about in the land exultingly. Surely Allah loves not any self-conceited boaster,” (xxxi 18).
(Hadith #165) It is narrated on the authority of ‘Abdullah b. Mas’ud that the Messenger of Allah (صَلَّى اللهُ عَلَيْهِ وَ سَلَّمُُ) observed: None shall enter the Fire (of Hell) who has in his heart the weight of a grain of mustard seed of Iman and none shall enter Paradise who has in his heart the weight of a grain of mustard seed of pride.
(Hadith #166) It is narrated on the authority of ‘Abdullah that the Apostle of Allah (صَلَّى اللهُ عَلَيْهِ وَ سَلَّمُ) observed: He who has in his heart the weight of a grain of mustard seed of pride shall not enter Paradise.