What is the ruling on one who abandons prayer for multiple days out of laziness, and is that considered disbelief (kufr)? How does one repent and atone? And is it obligatory to make up the missed prayers?

Illness is not an excuse to abandon prayer as long as one's intellect is present. The sick person must pray according to their ability. Abandoning prayer during illness is a grave error that necessitates repentance and making up the missed prayers. The four-rak'ah prayers missed during travel must be made up in full. Repentance is achieved through remorse and a firm resolve not to return to abandoning prayer. Jurists have differed regarding the ruling on one who abandons prayer out of laziness, whether it constitutes major disbelief or a sin.