Rehat is Guru Sahib's Hukam, Bhaana etc. These Pangtia make it clear that if we don't accept Guru Sahib's Hukam (including all Rehats as these are Hukams of Guru Sahib) then Guru Sahib will not be pleased with us.
ਕਹੈ ਪ੍ਰਭੁ ਅਵਰੁ ਅਵਰੁ ਕਿਛੁ ਕੀਜੈ ਸਭੁ ਬਾਦਿ ਸੀਗਾਰੁ ਫੋਕਟ ਫੋਕਟਈਆ ॥
If God says one thing, and the soul-bride does something else, then all her decorations are useless and false.
ਆਪਣਾ ਭਾਣਾ ਤੁਮ ਕਰਹੁ ਤਾ ਫਿਰਿ ਸਹ ਖੁਸੀ ਨ ਆਵਏ ॥
If you walk in accordance with your own will, then your Husband Lord will not be pleased with you.
ਸੋ ਸਿਖੁ ਸਖਾ ਬੰਧਪੁ ਹੈ ਭਾਈ ਜਿ ਗੁਰ ਕੇ ਭਾਣੇ ਵਿਚਿ ਆਵੈ ॥
He alone is a Sikh, a friend, a relative and a sibling, who walks in the Way of the Guru's Will.
ਆਪਣੈ ਭਾਣੈ ਜੋ ਚਲੈ ਭਾਈ ਵਿਛੁੜਿ ਚੋਟਾ ਖਾਵੈ ॥
One who walks according to his own will, O Siblings of Destiny, suffers separation from the Lord, and shall be punished.
Another point we can get from the first Pangti is that we may have all sorts of Shingaars, for Gursikhs this is our Bana, our Shastars, Khandai, Chakkars that we adorn, but if we just adorn these and don't accept the Hukams of Guru Sahib then they are useless. If we don't keep Rehat, wake up at Amritvela and Jap Naam then our outwardly Shingaars are useless, we only wear these to please Guru Sahib, but if we don't listen to all Hukams of Guru Sahib's then they are pointless.
ਮੈ ਸਭਿ ਸੀਗਾਰ ਬਣਾਇਆ ਅੰਮਾਲੀ ਬਿਨੁ ਪਿਰ ਕਾਮਿ ਨ ਆਏ ॥
I have adorned myself with all sorts of decorations, O my friend, but without my Husband Lord, they are of no use at all.
ਕੀਓ ਸੀਗਾਰੁ ਮਿਲਣ ਕੈ ਤਾਈ ਪ੍ਰਭੁ ਲੀਓ ਸੁਹਾਗਨਿ ਥੂਕ ਮੁਖਿ ਪਈਆ ॥7॥
She may adorn herself to meet her Husband Lord, but still, only the virtuous soul-bride meets God, and the other's face is spat upon. ||7||
ਮੁੰਧੇ ਪਿਰ ਬਿਨੁ ਕਿਆ ਸੀਗਾਰੁ ॥
O soul-bride, without your Husband Lord, what good are your decorations?
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥