What does the Muslim say when he hears the Muezzin saying "Achhadou" (I bear witness)?

وَأَنَا أَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللهُ وَحْدَهُ لَا شَرِيكَ لَهُ، وَأَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُهُ، رَضِيتُ بِاللهِ رَبًّا، وَبِمُحَمَّدٍ رَسُولًا، وَبِالْإِسْلَامِ دِينًا

And I bear witness that none has the right to be worshipped except Allah, alone, without partner, and that Muhammad is His salve and Messenger. I am pleased with Allah as a Lord, Muhammad as a Messenger and Islam as a religion.