Allah the Almighty said:
"Put your trust in Allah if you are believers indeed."
He the Most Exalted said:
"The believers are only those who, when Allah is mentioned, feel a fear in their hearts and when His Verses (this Qur'an) are recited unto them, they (i.e., the verses) increase their Faith; and they put their trust in their Lord (Alone)."
"O Prophet (Muhammad (May the peace and blessing of Allah be upon him) ) Allah is sufficient for you and for the believers who follow you."
"And whosoever puts his trust in Allah, then He will suffice him."
Narrated Ibn Abbas (May Allah be pleased with him)
"Allah (Alone) is sufficient for us, and He is the Best Disposer of affairs (for us)," was said by Ibrahim (May Allah be pleased with him) when he was thrown into the fire; and it was said by Muhammad (May the peace and blessing of Allah be upon him) when they (i.e. hypocrites) said, "Verily the people (pagans) have gathered against you (a great army), therefore, fear them, but it only increased them in Faith".
(Al-Bukhari and An-Nasa'i)