Explanation

The Niyat (intention) for Roza (fasting) is the spiritual foundation of your worship. It is the conscious decision and firm resolve in your heart that you intend to fast the following day solely for the sake of Allah. While reciting a specific formula in Arabic or your own language helps in focusing your mind and reaffirming your commitment, the essence of the Niyat lies in your heart's true intention before the time of Fajr. It marks the transition from normal daily habits to an act of devotion, ensuring that every moment of your fast is recognized as an act of worship.

Is there a Quranic Or Hadith reference?

While the Quran mandates the act of fasting (Surah Al-Baqarah: 183-185), the importance of Niyat is fundamentally rooted in the teachings of the Prophet Muhammad (PBUH). A famous Hadith in Sahih Bukhari states: 

"Actions are but by intentions, and every person shall have what they intended."

 This confirms that the internal resolve of the heart is what makes an act acceptable before Allah.

Summary

(English) The Niyat is a vital spiritual commitment where you resolve in your heart to fast for the sake of Allah. Though verbalizing the intention is a helpful and common practice to gain focus, the core requirement is your sincere internal resolve. It transforms your daily life into an act of worship, provided it is done with complete sincerity before the dawn prayer begins.

(Hinglish) Roza ki Niyat asal mein dil ka pakka irada hai ki aap Allah ki khushi ke liye roza rakh rahe hain. Zuban se dua ya alfaaz kehna ek behtareen tariqa hai apne mind ko focus karne ka, magar asli Niyat aapka dil ka irada hi hota hai. Yeh irada Fajr ki azan se pehle hona chahiye taaki aapka poora din Allah ki ibadat mein shumar ho.

Kya Roza rakhne ke liye Niyat ko sirf dil mein karna kaafi hai, ya zuban se kehna bhi lazmi hai?