Allah, the Exalted, says:

"And shun lying speech (false statements).'' (22:30)

"And follow not (O man, i.e., say not or do not or witness not) that of which you have no knowledge.'' (17:36)

"Not a word does he (or she) utter, but there is a watcher by him ready (to record it).'' (50:18)

"Verily, your Rubb is Ever Watchful (over them).'' (89:14)

"And those who do not witness falsehood...'' (25:72)

1550. Abu Bakrah (May Allah be pleased with him) reported: The Messenger of Allah (PBUH) said, "Shall I not inform you of one of the gravest of the cardinal sins?'' We said: "Yes, O Messenger of Allah!'' He (PBUH) said, "To join others as partners with Allah in worship and to be undutiful to one's parents.'' The Messenger of Allah (PBUH) sat up from his reclining position (in order to stress the importance of what he was going to say) and added, "I warn you making a false statement and giving a false testimony. I warn you against making a false statement and giving a false testimony.'' The Messenger of Allah (PBUH) kept on repeating this (warning) till we wished he should stop.
[Al-Bukhari and Muslim]

Commentary:  The contents of this Hadith make the gravity of making a false statement abundantly clear. How unfortunate indeed it is that, like other major sins, the evil of giving false testimony is very common among the present-day Muslims. May Allah prevent us from it.