buying property and getting cash back at closing

Hello,

Has anyone heard of properties with equity that are being sold to buyers where the seller is allowing the buyer to get cash out of the equity at closing . I am in California and would like to know if anyone is experienced or has any knowledge of this way of puchasing property .

Ex: house for sale 300k and has 100k in equity
buyer purchases the property and gets back 50k at closing of escrow