Srimad Bhagavatam Canto 12, Chapter 03, Text 30

SB 12.3.30

yada mayanrtam tandra
 nidra himsa visadanam
soka-mohau bhayam dainyam
 sa kalis tamasah smrtah
 
Translation: 
 
When there is a predominance of cheating, lying, sloth, sleepiness, violence, depression, lamentation, bewilderment, fear and poverty, that age is Kali, the age of the mode of ignorance.
 
Purport: 
 
In Kali-yuga, people are almost exclusively devoted to gross materialism, with hardly any affinity for self-realization.
Srimad Bhagavatam Canto 12, Chapter 03, Text 29
Srimad Bhagavatam Canto 12, Chapter 03, Text 31