Abu Hurairah (May Allah be pleased with him) reported:
The Prophet ﷺ said, "When one of you sneezes he should say: 'Al-hamdu lillah (praise be to Allah),' and his brother or his companion should say to him: 'Yarhamuk-Allah (may Allah have mercy on you).' When he says this he should reply: 'Yahdikum-ullah wa yuslihu balakum (may Allah guide you and render sound your state of affairs)."'

[Al-Bukhari].

وعنه عن النبي ﷺ الله عليه وسلم الله عليه وسلم قال: "إذا عطس أحدكم فليقل: الحمد لله؛ وليقل له أخوه أو أصحابه: يرحمك الله، فإذا قال له: يرحمك الله، فليقل: يهديكم الله ويصلح بالكم" ((رواه البخاري)).