Narrated Abu Huraira
The Prophet(PBUH) said, “The part of an Izar which hangs below the ankles is in the Fire.” (Sahih Bukhari, Vol. 7, Hadith no. 678)
In Another hadith, Narrated by Abu Huraira

Allah’s Messenger (PUBH) said, “Allah will not look, on the Day of Resurrection, at a person who drags his Izar (behind him) out of pride and arrogance.” (Sahih Bukhari, Vol. 7, Hadith no. 5788)

In the Hadith quoted above, there is a general instruction to keep the trouser above the ankle, irrespective whether it is out of pride & arrogance or without pride & arrogance.

Moreover, can any human being claim to be as humble as the Prophet (pbuh)? Alhumdulillah, we Muslims believe that the Prophet (pbuh) was far more humble than anyone of us can ever be and he could never be as arrogant & proud as we can be at any given time. He was sent as a mercy (Al-Qur’an 21: 107) for all the creatures, yet he wore his lower garments above the ankles. Therefore we should obey the commandment of the Prophet (pbuh) in order to prosper in the hereafter. The Prophet (pbuh) is reported to have said:
“All my followers will enter Paradise except those who refuse.” They said, “O Allah’s Messenger! Who will refuse?” He said, “Whoever obeys me will enter Paradise, and whoever disobeys me is the one who refuses (to enter it).” (Sahih Bukhari, Vol. 9, Hadith no. 384)

Thus, it is incumbent upon the Muslim men to wear the pants/trousers/izars above the ankles. And Allah knows the best.