Mukhtasar Bukhari (Abridged) 968 — Is it allowed to specify certain

It was asked from Umm al-Mu'mineen Aisha Siddiqa (may Allah be pleased with her) whether the Messenger of Allah (peace and blessings be upon him) used to specify certain days for worship. She replied, "No, the worship of the Messenger of Allah (peace and blessings be upon him) was continuous, and who among you has the strength for what the Messenger of Allah (peace and blessings be upon him) used to have strength for?"