Replying to Athaan – Call of Prayer

Hadith:

Sayyiduna Umar bin Khattaab Radhiyallahu Anhu reports Rasulullah Sallallahu Alayhi wa Sallam said,

“When the Muazzin calls “Allahu Akbar Allahu Akbar” and one of you replies “Allahu Akbar Allahu Akbar”;
and then he calls, “Ash-hadu al-Laa Ilaaha Illallah” and you reply, “Ash-hadu al-Laa ilaaha illallah”;
and then he calls, “Ash-hadu anna Muhammadar Rasulullah” and you reply, “Ash-hadu anna Muhammadar Rasulullah”;
and then he calls, “Hayya Alas Salaah” and you reply, “Laa Hawla wa Laa Quwwata illaa Billah”;
and then he calls, “Hayya Alal Falaah” and you reply, “Laa Hawla wa Laa Quwwata illaa Billah”;
and then he calls, “Laa Ilaaha Illallah” and you reply, “Laa Ilaaha Illallah” from your heart, you will enter Jannah.”

(Muslim)