Re: asalamu alaykum
Wa Alaykum as salam, wa rahmatullah, wa barakaat.
It is my duty to respond with an equal or better response.
"And when you are greeted with a greeting, greet in return with what is better than it, or (at least) return it equally."
(Qur'an, An-Nisa 4:86)
The Prophet Muhammad
said: "On the Day of Resurrection I will intercede and say, 'O my Lord! Admit into Paradise (even) those who have faith equal to a mustard seed in their hearts.' "
Source - Sahih Al-Bukhari, Volume 9, Hadith 600