Is it permissible to create an online group for a weekly competitive challenge among members to perform specific acts of worship? Does this fall under Sufi practices? Did the Prophet (peace be upon him) or his Companions do it? What is the evidence from the Quran or Sunnah that permits this?

Competition in good deeds is commendable, but it is not permissible to specify adhkar (remembrances) by certain numbers or to dedicate some of them to specific days not prescribed by the Sharia (definition). Rather, one must follow the Prophetic guidance in the diverse forms of adhkar. It is preferable to conceal private acts of worship unless their display serves to teach others, while being keen on sincerity. A Muslim should engage frequently in all adhkar without a specific limitation not mentioned by the Lawgiver. One can compete in memorizing the Quran and Sunnah (definition), hastening to perform good deeds, and encouraging others without intending ostentation.