The black deva's flying shard magic: take the twig of a 榎 jia tree (Catalpa Bungei), the twig pointing north-west; twist it to the shape of a buckwheat grain, write the Sanskrit letter भ on each of its three faces, place it before the deva, recite his spell a thousand times then cast the charm into the house of a prosperous person, saying may his wealth come to me. 

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous

（修法）其法以榎木指乾方之枝。作喬麥與麥之形（即寶珠形），其三面書[8768]字，置之於本尊之前。誦本尊之根本咒一千遍而加持之，然後投於福人之家，謂彼之福德來集我家也。是曰大黑之飛礫法。

丁福保《佛學大辭典》