Is there any evidence to support spreading the feet a handspan apart while standing in prayer?

There is no evidence for the desirability of the worshiper spreading his feet apart by a handspan while standing in prayer. Those who described the prayer of the Prophet, peace and blessings be upon him, did not mention this, as narrated by Muhammad ibn Amr ibn Ata from Abu Humayd al-Sa'idi.

There is no basis in the Sunnah for the saying of some: "Leave a handspan between your feet," as Sheikh Ibn Uthaymeen mentioned.

However, the worshiper should not stick his feet together while standing, because it contradicts moderation. Rather, he should spread them apart moderately, without excessive closeness or excessive spreading, as stated in "Fatawa of the Permanent Committee."