his Rāmāyaṇa he even meets Rāma in person and gives testimony of Sītā's unblemished character.

Chapter 7 (Uttara Kanda) - Sarga 87
When night was over, the king, Raghava, went to the sacrificial 
  ground and summoned all the immensely energetic rishis. 
  Vasistha, Vamadeva, Jabali, Kashyapa, Vishvamitra, Dirghatapa, 
  the great ascetic Durvasa, Agastya, Bhargava, Shakti, Vamana, 
  Markandeya, the great ascetic Moudgalya, Bhargava Chyavana, 
  Shatananda, who knew about dharma, the energetic Bharadvaja, 
  Suprabha, Agni's son, many other sages who were firm in their 
  vows and all the kings who were tigers among men assembled. 
  Filled with curiosity, the extremely valiant rakshasas and the 
  immensely strong apes all these great-souled ones also 
  assembled.Kshatriyas, vaishyas and thousands of shudras all 
  of them also assembled, to see Sita take the pledge. All of them 
  came there and were like mountains made out of stone. 
  They heard the sage coming quickly, accompanied by Sita. 
  With her face cast downwards, Sita followed the rishi at the rear. 
  Her voice choked with tears and in her mind, she joined her 
  hands in salutation before Rama. The beautiful one could be 
  seen to advance, following the brahmana. Sita was behind 
  Valmiki and loud roars of praise arose. There were sounds of 
  uproar everywhere. On seeing her immersed in this great 
  misery, they were overcome by grief.