Narrated Ibn `Umar (may Allah be pleased with them):The Prophet ﷺ said, "We are an illiterate nation; we can neither write nor calculate. The month is like this and this, i.e., sometimes of 29 days and sometimes of thirty days.".
Commentary :
Allah, Exalted is He, decreed that the sighting of the new moon (crescent) should be usedto determine the timings of the lunar months. The sighting of the crescent marks the end of one lunar month and the beginning of another. Based on this sighting, many religious obligations are determined, such as fasting and Hajj.
In this hadeeth, Ibn ‘Umar (may Allah be pleased with him) stated that the Prophet ﷺ said: “We are an uneducated nation; we can neither write nor calculate,” meaning that we, as Arabs, are mostly uneducated or unlettered. The Arabic word ‘Ummi’ denotes “motherly,” which indicates the inability to read, write, or calculate.
Reference to arithmetic skills here means the use of astronomical calculation to track the movements of stars, lunar stages, and calculate times and dates. Arabs are predominantly unfamiliar with astronomical calculation, although a few have mastered it.
Therefore, Islam assigns clear signs and obvious marks for acts of worship that require no astronomical calculation. Then, the Prophet ﷺexplained by the use of sign language to clarify for both the deaf and the non-Arabs. He ﷺ said: “The lunar month is such and such.” The narrator said: “He ﷺ pointed with his hands to indicate that the lunar month is either twenty-nine or thirty days. He ﷺ first pointed with all ten fingers of his hands twice, and folded the thumb the third time, to indicate twenty-nine days; and then gestured with his two hands thrice, to indicate thirty days.
A lunar month does not exceed thirty days and is not less than twenty-nine days. The beginning of the month is marked by the sighting of the crescent after the sunset of the twenty-ninth day, and if the crescent is not sighted, the month is thirty days.
It is noteworthy that the description ‘Ummi (uneducated)’ is one of the attributes of perfection with which Allah, Exalted is He, endowed His Messenger ﷺ and praised him, even though it may be considered an attribute of imperfection with respect to others, because the practice of reading and writing is a means to acquire knowledge that often refines people’s personalities and elevates their status. Since Allah, Exalted is He, singled out the Prophet ﷺ for the earlier and latter knowledge without the need of learning how to read and write, it was a miracle in this respect, and an indication of the sincerity with which he ﷺ was described in the earlier heavenly books and by which was known to the previous nations. Allah, Exalted is He, Says (what means): {Those who follow the Messenger, the unlettered prophet, whom they find written in what they have of the Torah and the Gospel…} [Quran 7:157].
In his case, illiteracy is perceived as one of his greatest miracles, and the greatest honor conferred upon him, although it is indicative of apparent deficiency and inability for others.
It is also deduced from the hadeeth that the use of sign language is allowable to explain unclear information..