The word(s) "observance" appears 2 time(s) in 2 verse(s) in Quran in Muhammad Pickthal translation.

(1) O ye who believe! Observe your duty to Allah with right observance, and die not save as those who have surrendered (unto Him)

(سورة آل عمران, Aal-i-Imraan, Chapter #3, Verse #102)
(Arabic, Transliteration, Urdu (Ahmed Ali), Urdu (Jalandhry), Farsi, Yusuf Ali, Shakir, Picthal, Mohsin Khan, French, Spanish, Indonesian, Malay, German, Bosnian, Russian, Dutch, Italian, Portuguese, Tafsir - Jalal ad-Din, Tafsir - King Fahad Quran Complex)

(2) Then We caused Our messengers to follow in their footsteps; and We caused Jesus, son of Mary, to follow, and gave him the Gospel, and placed compassion and mercy in the hearts of those who followed him. But monasticism they invented - We ordained it not for them - only seeking Allah's pleasure, and they observed it not with right observance. So We give those of them who believe their reward, but many of them are evil-livers.

(سورة الحديد, Al-Hadid, Chapter #57, Verse #27)
(Arabic, Transliteration, Urdu (Ahmed Ali), Urdu (Jalandhry), Farsi, Yusuf Ali, Shakir, Picthal, Mohsin Khan, French, Spanish, Indonesian, Malay, German, Bosnian, Russian, Dutch, Italian, Portuguese, Tafsir - Jalal ad-Din, Tafsir - King Fahad Quran Complex)