Must one who cleanses himself (al-mustanji) look at his private parts to ascertain the purity of the area due to doubt about residual drops of urine, or is it sufficient for him to cleanse himself until he is fairly certain of its purity? And is water that splatters onto the foot during cleansing pure?

If a person performs istinja' (washing after relieving oneself) and believes with strong probability that the impurity has been removed, that suffices him. It is not prescribed for him to look at his private parts to verify its removal, nor is he obligated to inspect and scrutinize. After istinja', he should sprinkle water on his garment and trousers to avoid whispers (waswas). The water that splashes from istinja' is not ruled as impure unless it changes due to the impurity. If one has relieved himself and washed what is necessary, then he should not pay attention to splashed water or any drops on the garment or body.