Question: What is the ruling on fasting in Ramadaan when one does not pray?
Answer: The one who fasts but does not pray, his fasting is of no use to him, nor will it be accepted from him, nor will it free him from his indebtedness (of prayer). In fact, fasting is not required on him so long as he does not pray.
This is since one who does not pray is like a Jew and a Christian. So what do you think about a Jew or a Christian that fasts but yet remains upon his religion – is it accepted from him? No. Therefore, we say to this individual: “Repent to Allaah by praying, and (then) fast.” And whoever turns to Allaah in repentance, Allaah will accept his repentance.
Posted from: Advice for those Fasting in Ramadaan (Q&A)
Imaam Muhammad bin Saalih Al-‘Uthaimeen
48 Su’aalan fis-Siyaam (binothaimeen.org). Al-Ibaanah.com