لا أنامُ بسببِ عملِي.
"laa 2anaam(u) bi-sabab(i) 3amalii.
(1) it is "bi-sababi 3amalii", ie. in the 2iDaafa structure, because the phrase is in the genitive case by harf ب
(2) it is "sababi" (and not sababin) because this part is the muDaaf of the 2iDaafa (ie. "sababi 3amalii").
Nb: I add a note because some members are confused. Hope it helps.