Friends:

What is always & inevitably a sour source of Suffering?

 

The Blessed Buddha once said this:
Bhikkhus & Friends there are these Four Noble Truths. What four?
The Noble Truth of Suffering;
The Noble Truth on the Cause of Suffering;
The Noble Truth on the End of Suffering;
The Noble Truth on the Way to end Suffering...
These are the Four Noble Truths!
 

What, Bhikkhus & Friends, is the 1st Noble Truth of Suffering?
These Six Sources of Sensing are Suffering!
The sense source of the eye is Suffering...
The sense source of the ear is Suffering...

The sense source of the nose is Suffering...
The sense source of the tongue is Suffering...

The sense source of the body is Suffering...
The sense source of the mind itself is Suffering...
This is thus verily the 1st Noble Truth of Suffering!

Source (edited extract):
The Grouped Sayings of the Buddha. Samyutta Nikāya. [V:426]
section 56: Saccasamyutta. Thread 14: Sources...
 

More on these 6 Sense Sources (Āyatana):
https://What-Buddha-Said.net/drops/II/The_Source_of_All.htm
https://What-Buddha-Said.net/drops/II/Source_of_What.htm
https://What-Buddha-Said.net/drops/IV/Experiencing_Egolessness.htm
https://What-Buddha-Said.net/drops/II/Mistaken_Reference.htm
https://What-Buddha-Said.net/library/DPPN/wtb/a/aayatana.htm

More on these 4 Noble Truths (Cattari Ariya Saccani):
https://www.accesstoinsight.org/lib/study/truths.html
https://What-Buddha-Said.net/drops/IV/Clustered_Truths.htm
https://What-Buddha-Said.net/library/DPPN/wtb/s_t/sacca.htm
https://www.accesstoinsight.org/ptf/dhamma/sacca/index.html
https://What-Buddha-Said.net/drops/II/The_4_Noble_Truths.htm

Six Sour Sense Sources!