Whoever Sets a Bad Precedent Will Bear the Burden of Sin of Those Who Do it Until the Day of Resurrection
Question

                If a person dies, and leaves behind bad deeds and bad things, will these bad things accumulate? Meaning if there was a father who set a bad example for his children, and his children grow up following in their father’s footsteps, will this father bear the burden of his children's sins?
Praise be to Allah.
      If a person dies having done actions that were contrary to 
      Islam, and others such as children, friends, neighbours and so on followed his example, then he bears the burden (of sin) of what he did and 
      the burden of those who did the same, following his example, without that 
      detracting from their burden of sin in the slightest. Muslim (1017) 
      narrated that Jareer ibn ‘Abd-Allah (may Allah be pleased with him) said: 
      The Messenger of Allah (may the peace and blessings of Allah be upon him) said: “Whoever sets a good precedent in Islam 
      will have the reward for that and the reward of those who do it after him, 
      without that detracting from their reward in the slightest. And whoever 
      sets a bad precedent in Islam will bear the burden of sin for that, and 
      the burden of those who do it after him, without that detracting from 
      their burden in the slightest.” 

    Ibn ‘Allaan said: 

    “Whoever sets a bad precedent in Islam” means sin, even if it 
    is small, if he does it and his example is followed, or if he promotes it or 
    helps others to commit it. “Will bear the burden of sin for that”, means, 
    for having done it. “And the burden of those who do it after him, without 
    that detracting from their burden in the slightest.” End quote. 

    Daleel al-Faaliheen, 2/136 

    Shaykh Ibn ‘Uthaymeen said: 

    This is a warning against setting a bad precedent, and shows 
    us that whoever sets a bad precedent will bear the burden of sin for that 
    and the burden of those who do it, until the Day of Resurrection, even if it 
    was on a small scale at first, then it became more widespread; he will bear 
    the burden of its spreading. For example, if one person granted a concession 
    to one other person with regard to something permissible that became a clear means leading to something impermissible or close to it, if that became 
    widespread because of the fatwa given to people, then the burden will be 
    upon him as will the burden of those who did it until the Day of 
    Resurrection. End quote.

    Sharh Riyaadh al-Saaliheen, p. 
    199  

    It was narrated that Ibn Mas‘ood (may Allah be pleased with 
    him) said: The Messenger of Allah (blessings and peace of Allah be upon him) 
    said: “No soul is killed unlawfully, but there is a share of the sin on the 
    first son of Adam, because he was the first one to set the precedent of 
    killing.” 

    Narrated by al-Bukhaari (3336) and Muslim (1677). 

    Al-Nawawi said: 

    This hadeeth represents one of the basic principles of Islam, 
    which is that anyone who introduces any kind of evil will bear the burden of 
    sin of everyone who follows his example in doing that until the Day of 
    Resurrection. End quote. 

    So the father who gives his children a bad upbringing and is 
    a bad example for them, and they follow him in his deviant conduct, will 
    bear the burden of his children’s sin, because he was the cause of their 
    deviating; the children will also bear the burden of their own actions in 
    full and nothing will be detracted from it. 

    What this father should have done was to give his children a 
    good upbringing and fulfil the responsibility that Allah placed upon his 
    shoulders in the best manner. 

    The Messenger of Allah (blessings and peace of Allah be upon 
    him) said: “Each of you is a shepherd and each of you is responsible for his 
    flock. … A man is the shepherd of his household and is responsible for his 
    flock.”

    Narrated by al-Bukhaari (7138) and Muslim (1829) 

    Shaykh Ibn ‘Uthaymeen said: 

    The man is the shepherd of the members of his household, his 
    wife, his son, his daughter, his sister, his paternal aunt and his maternal 
    aunt. He is the shepherd of members of his household and he is responsible 
    for his flock; he must take the best possible care of them because he is 
    responsible for them. End quote. 

    Sharh Riyadh al-Saaliheen, p. 
    337 

    And Allah knows best.