From what Macbeth says, does, and what others say about him, how do we know he’s a commanding figure, worthy of respect in Scotland?

At the beginning of the play, Macbeth is portrayed as a valiant, loyal soldier and leader who is worthy of King Duncan's praise and is respected throughout Scotland. In act one, scene two, the Captain praises Macbeth by saying,

But all’s too weak, For brave Macbeth—well he deserves that name—Disdaining fortune, with his brandished steel, Which smoked with bloody execution, Like valor’s minion carved out his passage Till he faced the slave; Which ne'er shook hands, nor bade farewell to him, Till he unseamed him from the nave to th' chops, And fixed his head upon our battlements. (Shakespeare, 1.2.15-24).

After hearing about Macbeth's accomplishments on the battlefield, King Duncan responds by calling Macbeth "O valiant cousin! Worthy gentleman!" (Shakespeare, 1.2.25). When Ross enters the scene, he informs King Duncan about Macbeth's valiant exploits against the Norwegian forces and the former Thane of Cawdor by telling him,

. . . Norway himself, with terrible numbers, Assisted by that most disloyal traitor, The thane of Cawdor, began a dismal conflict, Till that Bellona’s bridegroom, lapped in proof, Confronted him with self-comparisons, Point against point, rebellious arm 'gainst arm, Curbing his lavish spirit; and to conclude, The victory fell on us. (Shakespeare, 1.2.51-58)

After learning about Macbeth's courage and achievements, King Duncan once again praises Macbeth by calling him "Noble Macbeth." Following the victories, King Duncan gives Macbeth the title Thane of Cawdor as a reward for his heroic, gallant effort on the battlefield. Macbeth also reveals that he is a loyal, commanding figure by addressing King Duncan in act one, scene four. Macbeth tells King Duncan,

The service and the loyalty I owe In doing it pays itself. Your highness' part Is to receive our duties, and our duties Are to your throne and state children and servants, Which do but what they should, by doing everything Safe toward your love and honor. (Shakespeare, 1.4.23-27)

Macbeth's favorable reputation as a respected, valiant soldier contributes to his role as a tragic hero.