What is the ruling on uttering the Tasleem in prayer with a "qamariyah lam," and does that invalidate the prayer?

Peace is one of the pillars of prayer. Scholars have differed on the obligation of defining "Salam" with "Al" (the definite article) and whether the prayer of one who omits it is valid. Some, like Al-Shafi'i and a narration from the Malikis and Ibn Hazm, hold that saying "Salam 'alaykum" is sufficient, citing Quranic verses where "Salam" appears without the definite article and arguing that the tanwin (nunation) serves the purpose of definition. Others, however, believe it is not sufficient due to a change in wording and meaning. In summary, the matter is broad, and omitting or including "Al" does not affect the validity of the prayer, especially if done out of error or due to a lack of proficiency in Arabic pronunciation.