Is thinking about religious matters and the problems of the Ummah during prayer sinful and does it necessitate prostration of forgetfulness (sujood as-sahw)?

There is no sin in contemplating matters of religion during prayer, nor does it invalidate the prayer, nor does it necessitate a prostration of forgetfulness (sujud sahwi), even though some scholars have disliked contemplating during prayer, even if it pertains to matters of the Hereafter. Laziness in prayer is blameworthy, and it is sunnah to enter prayer with energy and a heart free from distractions, as the Prophet, peace and blessings be upon him, said: "A believer receives nothing from his prayer except what he understands."