Is it sunnah or fardh for men to wear their trousers above their ankles?

All praises be to Allaah, Lord and Sustainer of the worlds, and may the peace and blessings of Allaah be upon our Prophet Muhammad (peace be upon him) and upon his family and companions.

"Isbaal" is wearing one's garment below the ankles and it is forbidden because:

The Messenger of Allaah (peace and blessings of Allaah be upon him) said "Whatever of the izaar (lower garment) is below the ankles is in the Fire" al-Bukhaari,

And he said; "There are three whom Allaah will not look at or praise on the Day of Judgement and theirs will be a painful punishment: the one who wears his garment below his ankles, the one who reminds others of his favours, and the one who sells his product by means of making false oaths". reported by Muslim.
And there are other reports concerning the issue. The report concerning Abu Bakr (may Allaah be pleased with him) who said, "O Messenger of Allaah, my izaar slips down if I do not pay attention to it." the Messenger of Allaah (peace and blessings of Allaah be upon him) said: "You are not one of those who do it out of pride." Reported by al-Bukhaari, is specific for Abu Bakr (may Allaah be pleased with him) and not everyone else because every one of us has some pride in him whether he expresses it or not.

And even if one lowers his garment without pride it is not permissible because of the hadith mentioned above which does not make pride a condition for prohibition of Isbaal.

The question whether this Fard or sunnah is irrelavent here because this is a prohibition and the Messenger of Allaah (peace and blessings of Allaah be upon him) said, "when I order you to do something then do as much as you are able to and when I prohibit you from something then leave it" (narrated Muslim).
So, what is prohibited is not conditioned with ability rather it must be given up.

And Allah the Most Knowledgeable knows what is best and most correct.