I asked: How does mubāhāt (boasting) occur, what does it lead to, and how far does its harm reach? He answered me as follows: Mubāhāt occurs through knowledge and wealth. Boasting with knowledge is as follows: Constantly engaging in the pursuit of knowledge, memorizing extensively and persisting in memorization, receiving hadith from many hadith transmitters, and being able to answer immediately when asked a question, whether to oneself or to others. By this behavior, one seeks to rise by finding the truth or to show that one is superior to others and more learned than them. To show that he is more learned than his companion, he immediately cites a hadith. If his companion is about to mention a hadith, he says he knows it, with the intention of boasting and being superior to him.
Boasting with deeds is as follows: When one gathers with those who perform dhikr (remembrance of God), engage in jihād (struggle in the way of God), perform prayer, or do good deeds, if someone else is about to pray, he stands up to pray out of concern that the other will appear superior to him. If someone else prays beside him, he does not want him to pray so that his own virtue will be seen. If they pray together, he prolongs the prayer. Even if his companion becomes tired and gives up the prayer, he wants to appear superior and for those who are knowledgeable or those who pray with him to see themselves as small and him as superior. The same applies to fighting in battle; he wants to get ahead of others, to be in front while others are behind. He forces himself to attack the enemy and attacks with all his strength so that he may be seen as superior to his companion and more virtuous than him. If he were to be killed at that moment, perhaps all his reward would be lost, and he would not be safe from Allah's punishment. (This matter) applies to other deeds as well. (Riʿāya, 129)
Mubāhāt regarding the dunyā (worldly life) is as follows: For example, one boasts with buildings. He makes expenditures for his close neighbors, relatives, friends, colleagues, and others in his circle that he would not make if he were alone. If he were to build a building for himself, he would spend excessively for the sake of boasting, so that he may be superior and no one surpasses him. In acquiring worldly wealth, he works harder so that no one surpasses him, and so that he may be elevated by acquiring wealth and having his name mentioned. He behaves similarly with regard to servants and household goods. (Riʿāya, 130)