A person once sneezed and thereafter loudly recited, “Alhamdulillah!” Hazrat Moulana Ashraf Ali Thanwi (rahmatullahi ‘alaih) was engaged in writing his correspondences at the time. When he heard this person recite “Alhamdulillah”, Moulana Thanwi (rahmatullahi ‘alaih) replied, “Yarhamukallah,” and thereafter said, “A considerate person will recite Alhamdulillah softly. On account of you reciting it aloud, I was forced to leave the work that I was engaged in to fulfil the obligation of replying to the duaa that you recited after sneezing.” Hazrat Moulana Ashraf Ali Thanwi (rahmatullahi ‘alaih) then said, “In such situations, when people are engaged in some work, then Alhamdulillah should be recited softly after sneezing. When I am among people, I always recite Alhamdulillah softly so that I will not inconvenience them by making it waajib upon them to reply”. Similarly, Hazrat Moulana Ashraf Ali Thanwi (rahmatullahi ‘alaih) would recite the verses of Sajdah Tilaawah in the Qur’aan Majeed softly so that he would not inconvenience others by causing the Sajdah to become waajib on them. (Malfoozaat Husnul Azeez pg.485)
Source: Ihyaauddeen.co.za