If urine falls on the leather slipper after performing the ablution for prayer, does the ablution become invalid?

The Shaykh : He says: If urine falls on the leather slipper after performing the ablution for prayer, does the ablution become invalid?
The answer is that it does not become invalid. However, if it touches his foot, he must wash it to purify it from its ritual impurity. As for the ablution, it remains valid, unless the urine belongs to the person who performed the ablution himself; in that case, his ablution becomes invalid due to the urine.