Starting Your Prayer with "Allahu Akbar" Is a Must

Ali ibn Abu Talib (may Allah be pleased with him) shared that the Prophet (peace be upon him) taught us: the prayer begins with purity, and saying "Allahu Akbar" makes everything outside the prayer off-limits, until we end it with the salutation of peace. (Sunan Abu Dawud, Hadith 61) عَنْ عَلِيٍّ رضى الله عنه قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه و سلّم ‏ "‏ مِفْتَاحُ الصَّلاَةِ الطَّهُورُ وَ تَحْرِيمُهَا التَّكْبِيرُ وَ تَحْلِيلُهَا التَّسْلِيمُ ‏"‏ ‏.‏ [سنن أبى داؤد ، رقم الحديث ٦١]