Ahadeeth that promise great reward for good conduct are conditioned
16-10-2018 | IslamWeb
Question:
Salam I have a question regarding the Hadith which states that the believer with good character will enter the highest level of Jannah. Does this include one who may have committed a lot of sins, major or minor? Will they be punished first? Jazakullah
Answer:
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad 
is His slave and Messenger.
The principle rule regarding the Ahadeeth that encourage people to do good by mentioning Allah’s promises and rewards, and those which warn people from evil by mentioning Allah’s threats and punishments; reward and punishment in these narrations depend on the fulfillment of conditions and the absence of impediments.
For instance, the Ahadeeth that promise a great reward for good deeds such as good conduct, for example, then its condition is that there should be no impediments that prevent the person from getting this reward. If there is an impediment like Shirk (associating partners with Allah), then the one who commits Shirk will be eternally in Hellfire (and therefore, is not entitled for the rewards of good conduct).
If the person is one who commits grave major sins, then his good deeds are weighed against his bad deeds, as it is known, then Allah may or may not forgive him. This person may enter Hellfire because of his sins and then eventually enter Paradise, provided he has fulfilled the Tawheed (i.e., not associating anything or anyone with Allah).
Shaykh Ibn Taymiyyah 
said in Majmoo’ Al-Fataawa:
“The texts that encourage people to do good and mentioning Allah’s rewards apply to a person provided that his deeds are sincerely devoted for the Sake of Allah, and coincides with the Sunnah. The Prophet was asked: “A man fights for pride and haughtiness, another fights for bravery, yet another fights for showing off; which of these (cases) is in Allah's Cause?" The Prophet said, "The one who fights so that Allah's Word (Islam) should be superior, fights in Allah's Cause."
Likewise, the texts that warn people from evil by mentioning Allah’s threats and punishments apply to a person provided he did not misinterpret (a religious text) or made Ijtihaad and was wrong in his judgement, because Allah has forgiven this Nation for things they do by mistake or out of forgetfulness.” [End of quote]
The benefits of mentioning the promise of Paradise as a result of performing certain acts are apparent to whoever ponders on them; such encouraging (people) to do acts of obedience, being keen on performing them, and hoping for the reward for doing them, and that they are a reason for entering Paradise.
Allah knows best.