Is the one afflicted with urinary incontinence exempt from performing tayammum for his defiled clothes, or should he pray with them directly? And what is the amount of excused impurity that is equivalent to "the size of a dirham"?

The majority of scholars are of the opinion that tayammum (dry ablution) for impurity is impermissible, due to the absence of evidence legislating it. Ahmad differed on this matter. However, Al-Thawri, Al-Awza'i, and Abu Thawr permit wiping over the site of impurity with earth.

Those who quantify impurity by the dirham have differed in defining its area. Some said it is the size of the upper joint of the little finger, others said it is the size of the little finger bent, and some said it is the size of a wound's opening. Perhaps the reason for this difference goes back to the varying sizes of minted dirhams. Malik indicated that what is meant is the dirham Baghli, i.e., the minted dirham.