A prayer was an attempt to communicate with or entreat a deity.
When Grigori Rasputin devoured the cakes which were supposed to have been poisoned and remained unharmed in December 1916, Prince Felix Yusupov became convinced Rasputin was possessed by the Devil and shot him in the back as he knelt in prayer. Purishkevich finished the job, shooting Rasputin repeatedly until he died and then beating his corpse in a fit of rage. (PROSE: The Wages of Sin)
Receiving a phone call from her mother in 2009, Donna claimed to be in church praying. In reality, she was a sat on a toilet within a cubicle while investigating Adipose Industries. (TV: Partners in Crime)
When Kate Stewart confirmed that “the President [was] on board” Boat One, the Twelfth Doctor mistakenly thought she was referring to the President of the United States, and stated that he didn't want Americans involved as they would "only start praying". (TV: Death in Heaven)