Recognizing Allah’s blessings and being thankful for them is a part of everyday etiquette in the sphere of Islam. This extends to instances where non-Muslims, irrespective of their faith, express thanks to Allah, such as when they sneeze and say "Alhamdulillah" (praise be to Allah).
On such occasions, it is expected that Muslims should act in a manner that reflects the spirit of Islam – they should respond through kindness, understanding, and an opportunity to share the message of faith but also through the practice of the "Dua when a misbeliever praises Allah after sneezing." These interactions weave a tapestry of mutual recognition among the believers about Allah’s blessings that go across religions and the world at large that appreciates divine blessings.
If a non-Muslim sneezes and praises Allah, the appropriate response is not to say "Yarhamuk Allah (may Allah have mercy on you)" but rather to say "Yahdeekum Allahu wa yuslih baalakum (may Allah guide you and set your affairs straight)." This is based on reports narrated by Abu Dawood (5038) and al-Tirmidhi (2739), who classified it as sahih.
Abu Moosa (may Allah be pleased with him) reported: "The Jews used to sneeze in the presence of the Prophet (blessings and peace of Allah be upon him) hoping that he would say to them 'May Allah have mercy on you' but he used to say: 'May Allah guide you and set your affairs straight." (al-Tirmidhi, 2739).
It is recommended to say this dua to a misbeliever after he praises Allah with kindness and respect. You can also explain that Muslims say "Alhamdulillah" after sneezing because it acknowledges Allah as the giver of health and helps the person understand the Islamic perspective and sharing a hadith about the benefits of saying "Alhamdulillah" adds context and strengthens their understanding of the practice. This approach is a polite and straightforward way to engage in a conversation about Islamic customs.
According to the principles of Islam, saying some dua upon a misbeliever's praise of Allah by sneezing has many effects. It establishes unity in diversity to facilitate interfaith social life among people with differing religious beliefs. On the other hand, it is also a chance for da’wah where Muslims can kindly explain what “Alhamdulillah” means in Islam as well as about health and wellness.
In essence, it demonstrates that Islam as a religion embraces compassion as well as a good attitude towards fellow humans. Moreover, responding with gratitude and giving out information could pave the way for more dialogue between Muslims and other people, leading to higher levels of tolerance. In general, these benefits will help foster good relationships and enhance appreciation for Muslims’ traditions.