2 – Words whose meaning becomes clear only in relation to something else, such as ʿan, min, fī, and the like.
Both of these first two categories convey meaning by linguistic convention, and the scholars are unanimous that uttering them invalidates the prayer—unless a recognised sharʿī excuse exists that prevents one from ruling the prayer void.
3 – Words that carry no conventional meaning at all, such as sighing, crying, or groaning. The stronger view is that these do not nullify the prayer, because in the language they are not regarded as speech. ʿAlī (may Allah be pleased with him) used to ask permission to enter upon the Prophet (peace and blessings be upon him) while the latter was praying, and would clear his throat for that purpose.
Benefit:
Shaykh al-Islām said: The more apparent opinion is that loud laughter (qahqahah) breaks the prayer, because it involves levity and playfulness incompatible with the very aim of worship.
Ibn al-Mundhir said: There is consensus that laughing invalidates the prayer.
The scholars disagreed over the identity of the middle prayer for which Allah urged special care when He said, “Guard all the prayers, and the middle prayer” (al-Baqarah 2:238). Many views have been recorded—up to seventeen—but the soundest opinion is that it is the ʿAsr prayer; the evidentiary basis for other views is weak.
Al-Bukhārī (2931) and Muslim (627) relate from ʿAlī (may Allah be pleased with him) that on the Day of the Trench the Prophet (peace and blessings be upon him) said, “May Allah fill their graves and their houses with fire, for they kept us busy from the middle prayer until the sun had set.” Once the Prophet has explained a matter, no further explanation is needed.
Al-Tirmidhī said: This is the view held by most of the scholars among the Companions.
Al-Māwardī stated: It is the opinion of the majority of the Successors. Ibn ʿAbd al-Barr said: It is the position of most hadith scholars. It is also the school of the two imams, Abū Ḥanīfah and Aḥmad; the majority of the Shāfiʿīs have adopted it, as have Ibn Ḥabīb, Ibn al-ʿArabī, and Ibn ʿAṭiyyah among the Mālikīs.