The Prophet (peace and blessings be upon him) said:
"When a person says, 'The people are ruined,' he is the most ruined of them all (or he is the one who ruins them by spreading his despair)."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 712
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[حم م د] عن أبي هريرة. مختصر مسلم ١٨٢٣.