Plutarch,
Life of Brutus 4.5-6 (tr. Bernadotte Perrin):
It was
then, they
say, that Pompey was
so
filled with
delight and admiration that he
rose
from his seat as Brutus approached, and
in the sight
of all embraced him as a superior.
ὅτε καί φασι Πομπήϊον ἡσθέντα καὶ θαυμάσαντα προσιόντος αὐτοῦ καθεζόμενον ἐξαναστῆναι καὶ περιβαλεῖν ὡς κρείττονα πάντων ὁρώντων.
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.