It is the practice among Hindus, and even among the other communities to perform Thulabara’, weighing one against materials and offering to God.
This is offered mainly to Lord Guruvayurappan, Guruvayoor, Kerala.

Right now people walk in have the child weighed against the material they have vowed to perform the Tulabaram and have the material submitted to God.
The Puranas prescribe a procedure for performing the Tulabharam.
The procedure.
1The parents of the child must fast on the day of the Tulabharam.
2.Perform pooja for Graha Devatas, Family Deity and Personal Deity.
3.Have a Yagashala prepared, perform Yaga for Ganapathy, Subrahmanya and Siva.
4.Also perform the Yaga for the Deity to whom the Tulabharam is offered.
5.Then the child should be weighed in a Balance and the offering , equal to the weight of the child,is to be submitted to the Lord.
6.In the case of Adults, they have to stand in the Balance, have their palms folded ‘repent their sins and Pray that the Tulabharam is completed successfully.
The child can be fed during the day of the Tulabharam and not the Adults.
Source:
Sri Siva Purana.
”
Tulabharam is a Hindu ritual that has been practised from Dwapara Yuga. Tulabharam means a person weighing himself or herself in a balance and pay in equal weight of gold, fruits or grains to God when one’s prayers are fulfilled. Temples in Tirupati, Guruvayur, Dwaraka, Udupi and several other towns practice such offerings. Recently, Guruvayur temple hit the headlines in newspapers when a businessman from Bangalore gave the temple his weight in gold – 70 kg. Tirupati temple hits the headlines now and then when famous politicians and film stars give something to god measure for measure. This is offered to the gods when their prayers are answered.
The earliest reference to a Tulabharam comes from the Mahabharata, about the great emperor Sibi. He was so famous his name is found in ancient Tamil Sangam literature in four places and later in hundreds of places. He was even praised in Buddhist Jataka stories and Borobudur (Indonesia) sculptures. Emperor Sibi was a just king. Lord Indra and Agni wanted to test him and came in the form of an eagle and a dove. When the dove came to Sibi for protection from the chasing eagle, Sibi was ready to offer anything to save the dove. The eagle asked him to give his flesh measure for measure. Sibi cut himself bit by bit but the pans in the balance were never equal. At last when he himself stood on the pan the Gods appeared in front of him and blessed him. The story is found in other Sanskrit works as well.”
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Can you pls give me the reference of Tulabharam in Siva Puranam?
Right now ,I am unable to get hold of Siva Purana book due to lock down.
More references may be found at https://en.m.wikipedia.org/wiki/Sixteen_great_gifts
Regards.