An-Nu‘man b. Bashir reported God’s messenger as saying, “Supplication is worship.” He then recited, “And your Lord said, If you call on me I will aswer you.”*
*Qur’an, xl, 60.
Ahmad, Tirmidhi, Abu Dawud, Nasa'i and Ibn Majah transmitted it.
Jabir reported God’s messenger as saying, “Do not invoke curses on yourselves, or on your children, or on your possessions lest you happen to do it at a time when God is asked for something and grants your requests.”