Asr is the prayer on which the Sunni legal schools most visibly differ over timing. The majority, the Maliki, Shafii and Hanbali schools, hold that its time begins when an object's shadow equals its own length, while the Hanafi school, dominant across much of South and Central Asia and Turkey, delays the onset until the shadow reaches twice the object's length. The practical result is that mosques following different schools in the same city may call Asr up to an hour or more apart, a divergence Muslims navigate as a matter of settled scholarly difference rather than dispute.
Because its window closes hard at sunset, and because prayer during the actual moment of sunset is discouraged, the tradition urges that Asr be prayed well within its time rather than pushed to the edge. Twelver Shia practice commonly prays Asr immediately after Dhuhr, treating the two as a joined pair.
The jurists' disagreement traces to two differently transmitted hadiths describing the angel Gabriel leading the Prophet in prayer at slightly different times on two successive days, texts the Hanafi school reads as establishing the later, two-shadow-length threshold and the majority schools read as showing only a permitted range within the shorter reckoning. The dispute survives into the present largely as a matter of settled convention rather than live controversy, though it resurfaced with the spread of digital prayer-time calculators and mobile applications in recent decades, which must build in a choice of juristic method and so make the old scholarly divergence newly visible to ordinary worshippers checking two different apps.