What is the meaning of trivial sins? What is the explanation of the Hadeeth mentioned in that regard?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

It was narrated on the authority of Sahl ibn Sa‘d that the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said: “Beware of the minor sins. For the example of the minor sins is like a group of people who descended to a valley. Then each brought a straw until they gathered (enough straw) to bake their bread. (Likewise) the trivial sins, when they are committed, destroy the person who commits them.”  [Ahmad and Al-Haafith Ibn Hajar: Hasan chain of narration]

There is also another narration reported by Imaam Ahmad and At-Tabaraani on the authority of Ibn Mas‘ood and also another narration by An-Nasaa’i and ibn Maajah on the authority of ‘Aa’ishah in which the Prophet, sallallaahu ‘alayhi wa sallam, said: “O ‘Aa’ishah! Beware of the trivial sins for Allaah Will Ask (you) about them.” [Ibn Hibbaan: Saheeh]

Trivial sins are sins which one does not pay much concern to, as As-Sindi stated in his commentary on Ibn Maajah.

Additionally, Al-Munaawi said: "Trivial sins are the sins which are minor, which in turn lead to the major sins."

Al-Ghazaali said: "(When committing minor) sins, one leads to another until one loses the essence of happiness by destroying the basic principles of faith at the end of his life."

Al-Munaawi said in his explanation of the example given in the Hadeeth: "This means that when minor sins accumulate and were not expiated, then they would be destructive. He (the Prophet, sallallaahu ‘alayhi wa sallam) did not mention major sins for they were rarely committed during the generation of the Companions, who used to refrain from them and thus, he warned them against committing what they might not pay attention to."

Also, Al-Ghazaali said: "Minor sins become major sins by regarding them as trivial and insisting upon them, for the more the slave of Allaah regards the sin as great, the more Allaah The Almighty Will Regard it as trivial and the more the slave of Allaah regards the sin as trivial, the more Allaah The Almighty Will Regard it as great."

Allaah Knows best.