Boastful attitude may caused by having lots of wealth, the beautiful face, or widely learned. Therefore, it is not amazing when this such virus may injects everyone. Anybody has to be cautious.
Anything we have, indeed, is originated from Allah and it may leaves us or we do leave it at any time. It is often happened in a trice.
Someone who commits good deeds is not proper to be boastful though. Even less until he thinks that the good deeds he did will bring him to the heaven or evade him from the hell-fire.
For them who have done good is the best [reward] and extra. No darkness will cover their faces, nor humiliation. Those are companions of Paradise; they will abide therein eternally (Quran Sura Yunus: 26)
When Ibnu Kathir interpreted this ayah, he commented, ‘they (companions of heaven) are actually not proper to get it due to their deeds, but because Allah’s mercy and generousity only.’ That’s it, indeed, if it’s not because of grace, guidance and power which is given by Allah, no one among us will do good deeds. Even though to throw away thorn from road.
Yet, it cannot be called a boastful to whom worship diligently because of his fear of Allah’s threat about the hell-fire, nor he do hope for the paradise. Both are not in contradiction with Allah’s willing.
Even, both fear and hope are two elements which is exist in everyone’s faith. They will not appear on oneself, unless he has certain belief (tasdiq al-jazm) toward the existence of the great living on the hereafter.
And fear a Day when no soul will suffice for another soul at all, and no compensation will be accepted from it, nor will any intercession benefit it, nor will they be aided. (Quran Sura al-Baqara:123)
A slave who fears of hell-fire or misses the paradise is not in contradiction with his love to Allah. It is because the dread of hell-fire or the yearning of paradise will not appear, but because he affirms what are informed by his beloved, Allah.
Afterward, as a proof of love, he feels a necessary to tie up to Allah’s law in undergoing this life. This is not a boastful attitude.
On the contrary, a boastful slave is he who thinks he can save from Allah’s threat without any necessary to affirm His ayahs, without any good deeds, without avoid sins, without any necessary to control his ‘creativity’ of Allah’s law.
Even more, without any hope for heaven nor fear of hell-fire, while thinking that it’s the true love. This is the dangerous virus. Let’s avoid it.