Manava Dharmashastra 2.125

2.125

āyuṣmān bhava saumyeti vācyo vipro 'bhivādane
akāraś cāsya nāmno 'nte vācyaḥ pūrvākṣaraḥ plutaḥ //

A Brahmana should thus be saluted in return, 'May'st thou be long-lived, O gentle one!' and the vowel 'a' must be added at the end of the name (of the person addressed), the syllable preceding it being drawn out to the length of three moras.