The shins of 'Abdullah bin Mas'ud

And the proof that the person who performs the deeds will be weighed (himself), is what has been established on the authority of the Prophet (‫صلى الله عليه و سلم‬) that he (صلى الله عليه وسلم) was sitting (one day) and some of the companions were around him. In front of them stood the noble companion 'Abdullah Ibn Mas'ud. Then (suddenly) the wind revealed the shins of 'Abdullah Ibn Mas'ud whereupon the companions started laughing.

So the Prophet (‫صلى الله عليه و سلم‬) said:

"What are you laughing about?"

They said:

"About his thin shins, O Messenger of Allah."

And he (Ibn Mas'ud) used to have very thin shins.

Upon which the Prophet (‫صلى الله عليه و سلم‬) said:

"By the One in Whose Hand is my soul, indeed they (his shins) will weigh heavier on the scale on the Day of Judgement than the mountain Uhud!"

The Prophet (‫صلى الله عليه و سلم‬) said about the thin shins of Ibn Mas'ud:

"They (his shins) will weigh heavier on the scale than the mountain Uhud!"

So what is it that made them heavy? 

Righteous actions!

Shaykh 'Abdul-‘Azeez ar-Raajihi, may Allah preserve him 

Translated by Salafi-Dawah.com.
​Source: Explanation of Usool-us-Sunnah, page 93. View a scan of the page here.