Manava Dharmashastra 2.130

2.130

mātulāṃś ca pitṛvyāṃś ca śvaśurān ṛtvijo gurūn
asāv aham iti brūyāt pratyutthāya yavīyasaḥ //

To his maternal and paternal uncles, fathers-in-law, officiating priests, (and other) venerable persons, he must say, 'I am N. N.,' and rise (to meet them), even though they be younger (than himself).