In a derasar (Jain temple), devotees engage in various forms of worship and chanting. The specific prayers and mantras can vary depending on the sect (Shwetambar or Digambar) and local traditions, but some universally respected chants and prayers include:

1. Namokar Mantra (Navkar Mantra):

This is the most fundamental and revered mantra in Jainism. It is recited to pay respect to the five supreme beings (Pancha Parameshti): ``` Namo Arihantanam Namo Siddhanam Namo Ayariyanam Namo Uvajjhayanam Namo Loe Savva-sahunam Eso Pancha Namokkaro, Savva-pavappanasano Mangalanam cha Savvesim, Padhamam Havai Mangalam ```

1. Khamasamano:

This is a prayer of forgiveness and humility, often recited before performing rituals in the temple.

1. Bhaktamar Stotra:

A highly revered Jain hymn composed by Acharya Manatungacharya, dedicated to Lord Adinath (Rishabhanatha).

1. Logassa Sutra:

This prayer is often recited to show devotion to the 24 Tirthankaras.

1. Prakrit or Sanskrit Stutis (Hymns):

Devotees may also chant various hymns praising the Tirthankaras and Siddhas.

1. Personal Prayers:

Many also recite their own prayers, seeking spiritual upliftment, forgiveness, and detachment.

During puja and rituals, specific mantras are chanted according to the ritual being performed, such as the Snatra Puja, Ashtaprakari Puja, or other temple-specific pujas.

Etiquette: Before entering the sanctum, it is customary to chant the Namokar Mantra and bow before the idols. Silence, humility, and reverence are always encouraged in the derasar.

Summary: The most universally chanted prayer in a derasar is the Namokar Mantra, along with other Jain stutis and prayers as per tradition and occasion.