Laudator Temporis Acti

Servius on Vergil, Aeneid 11.500:

For there were four things among the Romans that were related to showing respect: to dismount from your horse, to bare your head, to move out of the way, and to stand up. Even the heralds who preceded magistrates were said to shout these instructions.

quattuor namque erant apud Romanos quae ad honorificentiam pertinebant: equo desilire, caput aperire, via decedere, adsurgere. hoc etiam praecones praeeuntes magistratus clamare dicebantur.

Plutarch mentions three of these marks of respect (dismounting, standing up, and baring the head) when he describes the behavior of Sulla towards Pompey.

Plutarch, Life of Crassus 6.5-6 (tr. Bernadotte Perrin):

Sulla paid him honours not very often accorded to men who were older and of equal rank with himself, rising at his approach, uncovering his head, and saluting him as Imperator.

ὥστε Σύλλαν, ἃ πρεσβυτέροις καὶ ἰσοτίμοις οὐ πάνυ πολλάκις παρεῖχεν, ὑπεξανίστασθαι προσιόντος αὐτοῦ καὶ κεφαλὴν ἀποκαλύπτεσθαι καὶ προσειπεῖν αὐτοκράτορα.

Plutarch, Life of Pompey 8.2 (tr. Bernadotte Perrin):

For when Sulla saw him advancing with an admirable army of young and vigorous soldiers elated and in high spirits because of their successes, he alighted from off his horse, and after being saluted, as was his due, with the title of Imperator, he saluted Pompey in return as Imperator.

ὡς γὰρ εἶδεν αὐτὸν ὁ Σύλλας προσιόντα καὶ τὴν στρατιὰν παρεστῶσαν εὐανδρίᾳ τε θαυμαστὴν καὶ διὰ τὰς κατορθώσεις ἐπηρμένην καὶ ἱλαράν, ἀποπηδήσας τοῦ ἵππου καὶ προσαγορευθείς, ὡς εἰκός, αὐτοκράτωρ ἀντιπροσηγόρευσεν αὐτοκράτορα τὸν Πομπήϊον.

Plutarch, Life of Pompey 8.3 (tr. Bernadotte Perrin):

And the rest of his behaviour to Pompey was consonant with his first tokens of friendliness; he would rise to his feet when Pompey approached, and uncover his head before him, things which he was rarely seen to do for any one else, although there were many about him who were of high rank.

καὶ τἆλλα δὲ ἦν ὁμολογοῦντα ταῖς πρώταις φιλοφροσύναις, ὑπεξανισταμένου τε προσιόντι τῷ Πομπηΐῳ καὶ τῆς κεφαλῆς ἀπάγοντος τὸ ἱμάτιον, ἃ πρὸς ἄλλον οὐ ῥᾳδίως ἑωρᾶτο ποιῶν, καίπερ ὄντων πολλῶν καὶ ἀγαθῶν περὶ αὐτόν.

I don't see any of these passages cited in the index to Carl Sittl, Die Gebärden der Griechen und Römer (Leipzig: Teubner, 1890).

Related post: Marks of Respect (standing up and dismounting).