In those by Guru Arjan and Kabir, the word is used metaphorically. By the fullness the moon attains that day, Kabir is reminded of the Supreme Being who fills and pervades the objects of His creation. Guru Arjan says that those whom God through His grace perfects (makes full) are not entangled by desire and become attached to Him who is perfect, complete and full. In Sikh belief, days spent in remembrance of the Perfect One are alone regarded auspicious. However, by custom Puranmashi has come to be observed in Sikh places of worship with special gatherings and services. A marked feature is ablutions by pilgrims in sarovars, the holy tanks.
References :
1. Sabadarth Sri Guru Granth Sahib. Amritsar, 1964
2. Sahib Singh, Sri Guru Granth Sahib Dorian. Jalandhar, 1963