Is it obligatory for me to remember Allah and pray upon the Prophet (peace be upon him) when speaking with anyone, or should I also invite my interlocutor to do so?

There are weak hadiths regarding shaking hands, remembering Allah, and seeking forgiveness upon meeting. Some of these mention that if two Muslims shake hands, praise Allah, and seek His forgiveness, they will be forgiven. Another states that if two servants who love each other for the sake of Allah shake hands and send blessings upon the Prophet, they will not part until their sins are forgiven.

It is permissible for a Muslim to advise his brother and remind him of the remembrance of Allah. The pious predecessors used to advise and encourage one another to faith. An example of this is Mu'adh's saying: "Sit with us, let us believe for an hour." And the Companions would not part until one of them recited Surat Al-Asr to the other.

It is legislated at the end of a gathering to say the supplication for the expiation of the gathering: "Glorified are You, O Allah, and praised be You. I bear witness that there is no god but You. I seek Your forgiveness and repent to You," due to its virtue in forgiving the idle talk of the gathering. The Prophet, peace be upon him, also used to supplicate for his companions in a gathering by saying: "O Allah, apportion for us of Your fear that which will come between us and disobedience to You..."

The rule is that gatherings in which Allah is not remembered will be a source of regret for their participants, and they have been likened to the carcass of a donkey. Furthermore, gatherings in which Allah the Almighty is not remembered and the Prophet, peace be upon him, is not invoked with blessings are considered a "loss" or deficiency.

Therefore, it is preferable upon meeting to give advice, study knowledge, encourage good, and frequently remember Allah and remind others of Him. A Muslim should seize the opportunity to remember Allah and send blessings upon the Prophet in his gatherings. The remembrance of Allah can be done by discussing His verses or the circumstances of the Prophet, peace be upon him, and sending blessings upon him.