Mahabharata is stated as the longest poem ever written. It consists of over 100,000 slokas and 200,000 individual lines. Is it true? Or are there any other holy books that are longer than the Mahabharata?
Actually, the Sarala Mahabharata has 152,000 individual verses:
not an exact translation from the Sanskrit original, but a full-blown independent work. Sarala Mahabharat has 152,000 verses compared to 100,000 in the Sanskrit version wikipedia
There is also a Shaiva upapurana called the Shiva-rahasya-purana, which also consists of roughly 100.000 verses:
The book consists of twelve parts and has about one hundred thousand verses. wikipedia
Then of course there are many now lost works counting well over 100.000 verses. A few examples:
The Manusmriti, used to be 100.000 verses (source)
The Gorakshasamhita, used to be 100.000 verses (source)
The Lankavatara-sutra, used to be 100.000 verses (source)
The Brihatkatha, used to be 700.000 verses (source)
The Shukraniti, used to be 10.000.000 verses (source, 1.4-5)
The various Agamas, having sometimes astronomical amount of verses (source).
And the list goes on.
Epic of King Gesar is claimed to have more than one million verses, which would make it even longer than Mahabharata.
The epic is composed of a very large body of versions, each with many variants, and is reputed by some to be the longest in the world. Although there is no one definitive text, the Chinese compilation so far of just its Tibetan versions has filled some 120 volumes, more than one million verses, divided into 29 "chapters". Western calculations speak of more than 50 different books edited so far in China, India and Tibet.