Friends:

Careless Attention grows Mental Hindrances!

The Blessed Buddha once said:
When one attends carelessly and irrationally then:
Greed, Lust, and Sense-desire arise, increase, and expand...
Hate, Anger and Ill-will arise, increase, and expand...
Sloth, Lethargy and Laziness arise, increase and expand...
Agitation, Restlessness and Regret arise, increase and expand...
When one attends carelessly and irrationally then:
Doubt, confusion and uncertainty arise, increase and expand...
Furthermore the Awareness link to awakening does not arise!
The Investigation link to awakening does not arise!
The Energy link to awakening does not arise!
The Joy link to awakening does not arise!
The Tranquillity link to awakening does not arise!
The Concentration link to awakening does not arise!
The Equanimity link to awakening does not arise!
And if these qualities are present in mind, then they instantly cease, when
one attends carelessly, neglectfully, absentmindedly, sloppily, and irrationally.
However if one attends carefully and rationally, the 5 mental hindrances
do not arise and if already arisen, then they gradually fade out and cease!
Secondly, any of the 7 mental links to awakening, that has not yet arisen,
arise and is gradually completed by mental development by this repeated
reflection and meditation...

More on Attention, rational and careful ( yoniso manasikāra):
Careful_Attention, Careful_and_Rational_Attention

Source (edited extract):
The Grouped Sayings of the Buddha. Samyutta Nikāya.
Book [V:84-5] section 46: The Links. 24: Careless Attention...

Careless Attention!