Is it permissible to fast from speaking for three nights with the intention of seeking offspring?

Worshipping Allah Almighty through silence and refraining from speech is not permissible in Islam. Rather, it is an act of the pre-Islamic era (Jahiliyyah) that has been forbidden. The Prophet, peace and blessings be upon him, prohibited remaining silent from day to night, and commanded remembrance [of Allah] and speaking good. Abu Bakr Al-Siddiq also indicated that absolute silence is not permissible. As for the story of Zechariah, peace be upon him, his silence was a sign, not an act of worship. A person must either speak good or remain silent, and it is not permissible for him to vow silence. If he does vow it, he must expiate for it with an expiation for breaking an oath. Offspring are sought through obedience to Allah and diligent supplication, and contentment with Allah's decree is better for the servant.