Albert Barnes Commentary Job 2:12

"And when they lifted up their eyes afar off, and knew him not, they lifted up their voice, and wept; and they rent every one his robe, and sprinkled dust upon their heads toward heaven." — Job 2:12 (ASV)

And when they lifted up their eyes afar off — “When they saw him at the distance at which they could formerly recognize him without difficulty, disease had so altered his appearance that at first sight they did not know him” - Noyes.

They lifted up their voice — This is a common expression in the Scriptures to denote grief (Genesis 27:38; Genesis 29:11; Judges 2:4; Ruth 1:9; 1 Samuel 24:16, and often elsewhere).

We learn to suppress expressions of grief, but the ancients gave vent to their sorrows aloud.

They even hired persons to aid them in their lamentations, and it became a professional business for women to devote themselves to the task of making an outcry on occasions of mourning.

The same thing prevails in the East even now. Friends sit around the grave of the dead, or go there at different times, and give a long and doleful shriek or howl as an expression of their grief.

And they rent every one his mantle — See the notes at Job 1:20.

And sprinkled dust upon their heads toward heaven — This is another expression of sorrow (Nehemiah 9:1; 1 Samuel 4:12; Joshua 7:6; Ezekiel 27:30).

The indications of grief referred to here were common in ancient times. They remarkably resemble the way Achilles expressed his sorrow when informed of the death of Patroclus (Iliad xviii. 21-27).

A sudden horror shot through all the chief,
And wrapped his senses in the cloud of grief;
Cast on the ground, with furious hands he spread
The scorching ashes over his graceful head,
His purple garments, and his golden hairs,
Those he deforms with dust, and these he tears:
On the hard soil his groaning breast he threw,
And rolled and groveled as to earth he grew.
Pope

Up to this point, the feelings of the three friends were entirely kind, and everything they did expressed sympathy for the sufferer.