Bhai Manvir Singh explains thoroughly the importance of those doing seva at Gurdwara Sahib should abide by the hukam of the Guru. He states that those cooking langar should be GurSikh and strict followers of the Rehat Maryada. He states that a person is likely to be influenced by those who do service at the Gurdwara Sahib and it’s important for GurSikhs to lead by example.
He made particular attention to smokers and alcohol drinkers. He states that Sikhs have become enemies of Sikhs because Sikhs criticize other Sikhs. Sikhi in the last 50 years has been watered severely by those who don’t follow rehat and often criticize Amritdharis for maintaining a strict discipline.
A smoker should never hold a Chaur Sahib and do Chaur Seva as it’s disrespect to Guru Sahib.
Bhai Manvir Singh explains what Puratan Hukamnamas say about the topic.