Agastya Samhita
Agastya Samhita is the title of several works in Sanskrit text attributed to the ancient sage Agastya.
Pancharatra
One of the samhitas of the Pāñcarātrāgama is the Agastya Saṁhitā, which is about the worshipping of Rāma, Sītā, Lakṣmaṇa, and Hanumān, as laid down by Agastya. It is also known as Agastya-Sutīkṣṇa-Samvāda, as it is in the form of a conversation between the sages Sutīkṣṇa and Agastya.
There are also other works titled Agastya Samhita among the Pancharatra texts, which are different from Sutīkṣṇa-Agastya-samvāda.
Puranas
Sections of certain Puranas believed to have been written by Agastya are called Agastya Samhita as well.
A section embedded in Skanda Purana is known as Agastya Samhita, and sometimes called the Sankara Samhita. It was probably composed in late medieval era, but before the 12th-century. It exists in many versions, and is structured as a dialogue between Skanda and Agastya. Scholars such as Moriz Winternitz state that the authenticity of the surviving version of this document is doubtful because Shaiva celebrities such as Skanda and Agastya teach Vaishnavism ideas and the bhakti of Rama, mixed in with a tourist guide about Shiva temples in Varanasi and other parts of India.
Agastya Samhita is the name of one of the three sections of Garuda Purana which deals with the study of gems; the other two being the Brihaspati Samhita and the Dhanvantari Samhita which is a study on material science, jurisprudence and medicine.