Is it permissible to vow to pray 10 rak'ahs every time I talk about an unimportant matter or joke with friends during a specific period, with the allowance to postpone fulfilling the vow until after this period ends, and is this vow considered among recurring vows that necessitate a single expiation or multiple expiations?

It is advisable to preserve time and not waste it on what is not beneficial, and to emphasize the importance of avoiding vows, especially conditional ones, citing the hadith (definition): "Indeed, it brings no good, but only extracts from the miser."

As for the multiplicity of expiation, it depends on the wording of the oath and the intention of the one who swore it. If the swearer did not intend to repeat the expiation every time the sworn-upon act was done, then it does not multiply. However, if he intended that, then it multiplies with the repetition of the act. If a person swears to do something and then breaks it, then repeats the oath and breaks it again, the majority of scholars believe that only one expiation is required, based on the saying of Ibn Umar (may Allah be pleased with them both): "If you swear repeatedly, then it is one expiation."