Is it permissible to say, as a wird (regular devotional recitation): "Know that there is no god but Allah"?

The remembrance mentioned, "So know that there is no god but Allah," is part of a verse in Surat Muhammad. Repeating the verse for contemplation is permissible, as the Prophet, peace and blessings be upon him, spent the night repeating a verse. It is permissible to repeat a single verse in prayer for contemplation, admonition, and supplication, and this indicates the Prophet's diligence in worship. Taking the complete verse as a daily litany has not been authentically reported in the Sunnah (definition). However, the Sunnah states that taking the testimony of monotheism, "La ilaha illa Allah" (There is no god but Allah), as a litany is encouraged. Whoever says it a hundred times, it is equivalent to freeing ten slaves, one hundred good deeds are written for him, one hundred bad deeds are erased from him, and it serves as a protection from Satan. It is among the best of good deeds.