What is meant by the fitan in which the one who is sitting will be better than the one who is standing?

Firstly: 

The hadeeth referred to was narrated by Abu Hurayrah (may Allah be pleased with him), that the Prophet (Blessings and peace of Allah be upon him) said: “There will be tribulations during which one who sitting is better than one who is standing, and one who standing is better than one who is walking, and one who is walking is better than one who is running. He who exposes himself to them will be drawn to them and whoever find a refuge from them, let him seek protection therein.”

Narrated by al-Bukhaari (3601) and Muslim (2886). 

Secondly: 

Al-Haafiz Ibn Hajar (may Allah have mercy on him) said, commenting on the meaning of this hadeeth): 

The words “He who exposes himself to them” mean, the one who wants to find out about them and does not want to ignore them. 

“will be drawn to them” means: they will destroy him, because he will expose himself to destruction because of them.  

“whoever find a refuge from them” means a place where he may seek refuge from the evil (of these turmoils). 

“let him seek protection therein” means: let him withdraw to that place so that he may be safe from the evil of the turmoil. 

The explanation of this hadeeth is also found in Saheeh Muslim, in the hadeeth of Abu Bakr, which says: “When they come, whoever has camels let him stay with his camels,” — and he mentioned sheep and land. A man said: O Messenger of Allaah, what do you think if he does not have camels or sheep or land? He said: “Let him go to his sword and make it blunt with a stone, then let him try to find a way of escape if he can. End quote. 

Fath al-Baari (13/30); see also Sharh Muslim by al-Nawawi, 18/9 

Thirdly: 

What is meant by these tribulations is what will happen among the Muslims of fighting, hatred and enmity, or disputes over worldly matters, without stating which of the two parties is in the right or which is in the wrong. 

Al-Haafiz Ibn Hajar (may Allah have mercy on him) said: 

With regard to the words “one who sitting is better than one who is standing”, Ibn al-Teen narrated from al-Dawoodi that it seems that what is meant is those who are fully involved in the turmoil and is part of it, i.e., some of them will be more involved in that than others. The highest of them in that will be the one who is running, who will be a cause of stirring them up; then comes the one who is keeping them going, and he is the one who is walking. Then comes the one who is involved in them, and he is the one who is standing. Then comes the one who is just looking on, and does not fight, and he is the one who is sitting. Then comes the one who is avoiding it, and is neither involved nor looking on, and he is the one who is lying down yet is awake. Then comes the one who does not do any of that, but he accepts it, and he is the one who is sleeping.

 What is meant by this listing of who is superior in goodness is the one who is less evil than the one above him in the details mentioned. 

This is a warning against tribulation and encourages us to avoid getting involved in it, and it tells us that its evil that a person may acquire from it will be according to how much he is involved in it.  End quote. 

Fath al-Baari, 13/30-31 

And Allah knows best.