Forgiveness of the Three who Remained Behind
It was the practice of the Holy Prophet (sa) that whenever he returned to Medina after a journey, he would go to the mosque and offer two rak‘at [units] of prayer. Thus, the Holy Prophet (sa) returned from Tabuk and entered Medina in the morning. He proceeded immediately to offer two rak‘at of prayer in the mosque.
(Musnad Ahmad bin Hanbal, Vol. 5, p. 414, Musnad Ka‘b bin Malik, Hadith 15865, Alamul Kutub, Beirut, 1998)
After offering his prayers, he sat down in the mosque in order to meet with everyone. Those who intentionally stayed behind from travelling to Tabuk without any reason had also come to see the Holy Prophet (sa). There were approximately 80 individuals who presented excuses for remaining behind. Despite the fact that the Holy Prophet (sa) knew the true reality of their false excuses, yet even then he accepted what they said and pardoned them. He would take their oath of allegiance and seek forgiveness for them.
(Sahih al-Bukhari, Kitabul Maghazi, Bab Hadith Ka‘b bin Malik, Hadith 4418)
However, as it has been mentioned in detail already, Hazrat Hilal (ra) bin Umaiyyah, Hazrat Murarah (ra) bin Rabi‘ and Hazrat Ka‘b (ra) bin Malik did not present any false excuses. As a result of this, Holy Prophet (sa) was displeased with them for some time. They prostrated before God Almighty and lamented before Him and implored for His forgiveness. Later, Allah the Almighty accepted their repentance and also mentioned the acceptance of their repentance in the Holy Quran.