What is meant by "temporary acts of worship" in the saying of Sheikh Ibn Uthaymeen: "The rule states that temporary acts of worship, if a person delays them beyond their appointed time without a valid excuse, are never valid from him," and what is the meaning of "are never valid from him"? And what is the explanation of this rule with examples?

Temporary acts of worship, such as the five daily prayers and the Ramadan (definition) fast, are not permitted to be delayed beyond their appointed times without a valid excuse. Whoever does so has committed a sin. Scholars have differed regarding the obligation of making up (qada') for someone who deliberately missed them: the majority of scholars are of the opinion that making them up is obligatory, while others, such as Ibn Hazm, Ibn Taymiyyah, and Ibn Uthaymeen, held that they are not to be made up and are not valid if made up by someone who did so. They argued that making up was prescribed for those with an excuse, such as sleep or forgetfulness, and that if someone who deliberately abandoned them repents, it is not legislated for him to make them up; rather, he should increase in voluntary acts of worship.