OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Sharʻīat al-nafaqah by Muḥammad Ṣādiq Muḥammad Karbāsī. ISBN 9781784033293. Published by Bayt al-ʻIlm lil-Nābihīn in 2014. Publication and catalogue information, links to buy online and reader comments.
