When you sneeze , then say:

Alḥamdulillāh
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Your companion should say:

Yarḥamukallāh
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to you then you should say:

Yahdīkumullāhu wa yuṣliḥu bālakum.
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When you sneeze, then say: All praises and thanks are to Allah.

Your companion should say: May Allah have mercy upon you.

When someone says Yarḥamukallāh to you then you should say: May Allah guide you and set your affairs in order.