What is the heaviest thing in the scale of the servant on the Day of Resurrection?

Question:
Your Eminence the Shaykh, the questioner asks: What is the heaviest thing in the scale of the servant on the Day of Resurrection?

Answer:
It is mentioned in the hadith: Tawhid (the oneness of Allah) is the greatest of good character; Tawhid and sincerity to Him are the greatest of good character. He created the Qur'an as Tawhid of Allah, obedience to Him, and following the Qur'an. So the greatest and best of character is Tawhid of Allah and sincerity to Him, followed by the rest of good character in dealing with people, in his prayer, in his fasting, in his Hajj, in his buying, in his selling, and in other matters. It is obligatory for the believer to be cautious of bad character and to take care of good character. The authentic hadith states: "You will not fill the bellies of your people with your wealth." The Prophet (peace and blessings be upon him) said: Allah the Exalted said in the testament of His Prophet (peace and blessings be upon him): I was asked about that by Aisha (may Allah be pleased with her), and she said: "His character was the Qur'an," meaning he took care of the commands of Allah, refrained from His prohibitions, and put on a pleasant face for people, as Allah the Exalted said: Good character is obedience to Allah, Tawhid of Allah, and sincerity to Him, and putting on a pleasant face, and not frowning at people, except for one who deserves that by being boycotted, except for one who deserves to be boycotted; then he frowns at him. If one openly commits sins and evil, he deserves to be boycotted and met with a gloomy face, unless he repents and returns to Allah. If he advises and guides, and if he repents, praise be to Allah; otherwise, it is obligatory to boycott him, as Ibn Abd al-Qarir (may Allah have mercy on him) said: "Boycotting one who openly displays sins is a Sunnah." It was said that he should be restrained, and it was made obligatory and emphasized, and it was said absolutely, as long as he is open about it, and one should not stand before him with a gloomy, frowning face. The point is that boycotting is a return to the Prophet's practice; the Prophet boycotted Ka'b ibn Malik and his two companions, and the Companions boycotted him for fifty nights because they lagged behind the expedition without an excuse, until Allah accepted his repentance. So, if one openly commits a sin and does not repent, he deserves to be boycotted. As for the believer with his upright brother, it is not permissible for you to frown at him; rather, you should meet him with a pleasant face, meaning a good face. As for one who openly displays sins and evil, it is obligatory to boycott him until he repents to Allah and abandons his sin until he regrets it; otherwise, it is obligatory to boycott him and discipline him by the rulers and to take action against him until he is upright upon the religion of Allah. And you, if you know that of him, he deserves to be boycotted if he has openly displayed the sin. And it is upon the ruler and the responsible parties to do what is obligatory regarding him. If he abandoned prayer, it is obligatory that he be disciplined until he prays; if he abandoned zakah, likewise; if he abandoned fasting, likewise; and so on.
Abandoning Hajj while having the ability, and so on, he is punished. Likewise, eating riba (usury or interest), likewise, drinking khamr (intoxicants). Whoever engages in a sin, it is obligatory that the command of Allah be established against him regarding it. If it is a hadd (fixed punishment), then a hadd; and if it is a ta'zir (discretionary punishment), then a ta'zir, if he has made it public. It is obligatory upon the rulers and the responsible parties to act against him until he abandons what Allah has forbidden him of the apparent sins. And it is obligatory to boycott him if he openly commits a sin, by those around him, his neighbors and others, until he repents to Allah and abandons the sin. As for the sin between him and Allah, that is His affair with Allah. As long as he has made it public, this is between him and Allah, the Exalted. And let everyone fear Allah. And may Allah send prayers and blessings upon our Prophet Muhammad.