Muhammad bin Ubaydullah al-Thaqafi says that Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) wrote: Whoever holds a testimony and does not give it when he saw (the event) or when he came to know of it, is only testifying (later) out of rancour.
This is munqati' (broken) between al-Thaqafi and Umar (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / 20597