Dua for fear of shirk

اللّهُـمَّ إِنّـي أَعـوذُبِكَ أَنْ أُشْـرِكَ بِكَ وَأَنا أَعْـلَمْ، وَأَسْتَـغْفِرُكَ لِما لا أَعْـلَم

O Allah, I take refuge in You lest I should commit shirk with You knowingly and I seek Your forgiveness for what I do unknowingly.