Sincere worship of Allah is important, as one must be completely dedicated when performing acts of worship like standing in prayer. The pious servants of Allah, such as Imam Zainul Abideen, taught believers how to worship with sincerity, as shown when his house caught fire while he prayed but he continued with total sincerity, saying he was trying to extinguish the fire of the hereafter.

1. SINCERITY IN IBAADAT
is very important for a believer. When one worships
Almighty Allah, he or she must be completely sincere and
dedicated.
When a person stands in Namaaz, then he should
remember that he is standing in the exalted court of Allah.
The pious servants of Allah taught us how to make Ibaadat
with sincerity.
One such example is Hazrat Sayyiduna Imam Zainul
Abideen .
He used to perform one thousand rakaats of nafil salaah
every night. One night whilst he was performing his nafils,
his house caught on fire. The people were rushing around
trying to put out the fire, but he continued his Namaaz
with total sincerity. After he completed his salaah, the
people told him that his house had caught on fire and yet
he continued reading his Namaaz without any showing
any sign of panic. He said,
“You were trying to extinguish this fire, and I was trying
to extinguish the fire of the hereafter.” [Khazinatul
Asfiyah vol.1 pg.31]