If you are unable to perform the prayers at any time by mistake or for any other special reason, then performing these prayers later is called kaza prayers. If the obligatory or obligatory prayers are missed, his deeds must be performed. If the sunnat or tahajjud nafl prayers cannot be performed, then the qaza does not have to be performed. Now what is the Vitr prayers to read kaza ? Sir! It is better to study. There is a difference of opinion among the scholars regarding the Witr prayer. Some say it is obligatory , some say it is Sunnah. In a word, it is better to read kaza. Sir! If you can perform Vitr , Fajr due to heavy sleep, you have to perform it as soon as you remember. It is narrated on the authority of Musa ibn Isma'il (R) from Abu Qatada (R). He said that the Prophet (peace and blessings of Allaah be upon him) was on a journey. He concentrated on one side and I concentrated on him too. Then he said: Notice. Then I say this one rider , these two riders , these three riders so we get to seven in the count. Then the Prophet (peace and blessings of Allaah be upon him) said: Look at our Fajr prayers. Then the rabbi said that their ears were closed (everyone fell asleep) and no one could wake up before the heat of the sun hit them. After waking up after waking up, they left the place, went a little farther, landed and performed aju. Then. After Bilal (R) gave the call to prayer, they first performed two rak'ats of Fajr Sunnah , then performed two rak'ats of obligatory prayers and left the place. Then they used to say to each other , "We have sinned by not performing the prayers at the appointed time." Upon hearing this, the Prophet (peace and blessings of Allaah be upon him) said: It is not wrong for a person to perform qiyaam prayers unintentionally. However, it would be wrong to perform the prayers intentionally while awake. Therefore, when one of you forgets to perform the prayer, he should perform it as soon as he remembers, and the next day he should perform the prayer of that time at his appointed time. (Sunan Abu Dawood , Hadith Number: 436 Hadith Man: Sahih).