Does the heel include the rough area above the prominent bone where hair does not grow, and what should a son do if that area on his father's foot is not washed during ablution?

The two ankles are the two protruding bones at the bottom of the leg on either side of the foot, and washing them along with the feet is an obligatory part of ablution (wudu'), based on the Almighty's saying: "and your feet to the ankles." It is obligatory to wash the entire ankles thoroughly. If any part of them is left unreached by water, one must repeat the ablution and the prayer as long as the time remains. However, if the time has passed, one is not obligated to repeat past prayers unless one was negligent.