And we—praise be to Allah—possess a clear criterion that Allah Himself has laid down, a plain definition of His friends: “those who believe and remain mindful of Him.” These, then, are the friends of Allah. Whoever shows hostility toward the friends of Allah, Allah says, “I have declared war on him,” that is, He has openly announced war against such a person. Anyone who opposes the friends of Allah is, therefore, at war with Allah—may He protect us—and whoever wages war against Allah is inevitably crushed and forsaken; he will never be able to stand his ground.
Allah, exalted is He, then said: “My servant does not draw near to Me with anything more beloved to Me than the duties I have made obligatory for him.” In other words, no one can come closer to Allah with anything dearer to Him than the obligations He has prescribed. This means that the obligatory acts are more beloved to Allah than the supererogatory ones. The five daily prayers, for example, are dearer to Allah than the night vigil and all other voluntary prayers; fasting the month of Ramadan is dearer to Him than fasting on Mondays and Thursdays, the six days of Shawwal, and the like. Every obligation is more beloved to Allah than every voluntary act.
The reason is that Allah has stressed the obligatory duties and bound His servants to them, and this alone is proof of how intensely He loves them. Because He loves them so greatly, He made them mandatory. As for the voluntary deeds, a person is free: if he wishes, he may perform extra acts and increase in goodness, and if he wishes, he may leave them. Nevertheless, the obligations are dearer to Allah and carry more weight. Strangely, Satan comes to people so that you find them perfecting their voluntary acts—during the night prayer, for instance, a person stands in deep humility, motionless, with a heart wholly present—yet when the obligatory prayers arrive, he fidgets, is assailed by whisperings, and his thoughts wander far and wide. This is nothing but Satan’s adornment. If you beautify a voluntary act, then the obligatory act is even more deserving of being beautified. So perfect the obligation, for it is dearer to Allah than the voluntary acts.