Anas (May Allah be pleased with him) reported:
When two men sneezed in the presence of the Prophet ﷺ, he responded to one with "Yarhamuk-Allah (may Allah have mercy on you)" and did not respond to the other. The latter said to him: "You invoked a blessing on this man but did not do so in my case." The Prophet ﷺ replied, "He praised Allah (i.e., he said 'Al-hamdu lillah') but you did not."

[Al-Bukhari and Muslim].

وعن أنس رضي الله عنه قال: عطس رجلان عند النبي ﷺى الله عليه وسلم الله عليه وسلم ، فشمت أحدهما ولم يشمت الآخر، فقال الذي لم يشمته: عطس فلان فشمته، وعطست فلم تشمتني؟ فقال:
"هذا حمد الله، وإنك لم تحمد الله" ((متفق عليه))