"Bhikkhus, do not think thoughts that are harmful and unwholesome, such as thoughts of sensuality, thoughts of ill-will, and thoughts of harming. What is the reason for this? Bhikkhus, these thoughts are not connected with benefit, they are not essential to the spiritual life, nor do they lead to disenchantment, to the fading of desire, to gradual ending, to tranquility, to direct knowing, to full awakening, to Nibbāna.

But, bhikkhus, when you do think, you should think: 'This is suffering'; you should think: 'This is the arising of suffering'; you should think: 'This is the ending of suffering'; you should think: 'This is the way of practice leading to the ending of suffering.' What is the reason for this? Bhikkhus, these thoughts are connected with benefit, they are essential to the spiritual life, they lead to disenchantment, to the fading of desire, to gradual ending, to tranquility, to direct knowing, to full awakening, to Nibbāna.

Therefore, bhikkhus, effort should be made to fully understand: 'This is suffering'; effort should be made to fully understand: 'This is the arising of suffering'; effort should be made to fully understand: 'This is the ending of suffering'; effort should be made to fully understand: 'This is the way of practice leading to the ending of suffering.'"