Does the existence of a disabled child indicate that their parents are not righteous, and that it is a punishment for their sins—as happened with the Prophet Sulaiman (peace be upon him)—and did Allah test any of His prophets or companions with a disabled child?

The presence of a disabled child does not necessarily mean that the parents are unrighteous, or that it is a punishment for their sins. Trials ( ابتلاء ) have diverse reasons and wisdoms, and are not solely a punishment for sins. Rather, they may be a purification, an expiation, and an elevation of ranks. Parents must accept what is decreed with patience, seeking reward from Allah, and contentment. They should treat their son kindly, avoid discontent and despair, and be careful not to harm him.

As for the story of Sulaiman (peace be upon him) and the Hadith "I will certainly go around to one hundred women tonight," considering it a punishment for his sin is a mere conjecture without proof. It is feared that this contains an audacity that contradicts the respect due to the prophets, for he (peace be upon him) forgot, and there is no accountability for forgetfulness. Some scholars considered what happened to him as a form of admonition specific to prophets due to their high status; they are discussed and admonished for matters for which others are not, and this was due to his oversight in not uttering "In sha' Allah" (if Allah wills), not due to a lack of reliance in his heart. The Hadith did not imply that a "half" person was born alive.

The question of whether prophets or companions were tested with a disabled child is a historical inquiry that is not related to a legal ruling.